[bacula/bacula] / bacula / kernstodo

                    Kern's ToDo List
                     08 February 2006

Major development:      
Project                     Developer
=======                     =========                         

Document:
- Does ClientRunAfterJob fail the job on a bad return code?
- Document cleaning up the spool files:
  db, pid, state, bsr, mail, conmsg, spool
- Document the multiple-drive-changer.txt script.
- Pruning with Admin job.
- Does WildFile match against full name?  Doc.
- %d and %v only valid on Director, not for ClientRunBefore/After.

Priority:
- Implement code that makes the Dir aware that a drive is an             
  autochanger (so the user doesn't need to use the Autochanger = yes 
  directive).

For 1.39:
- Detect resource deadlock in Migrate when same job wants to read
  and write the same device.
- Make hardlink code at line 240 of find_one.c use binary search.
- Queue warning/error messages during restore so that they
  are reported at the end of the report rather than being
  hidden in the file listing ...
- Fix Maximum Changer Wait (and others) to accept qualifiers.
- Look at -D_FORTIFY_SOURCE=2
- Add Win32 FileSet definition somewhere
- Look at fixing restore status stats in SD.
- Make selection of Database used in restore correspond to
  client.
- Implement a mode that says when a hard read error is
  encountered, read many times (as it currently does), and if the
  block cannot be read, skip to the next block, and try again.  If
  that fails, skip to the next file and try again, ...
- Add level table:
  create table LevelType (LevelType binary(1), LevelTypeLong tinyblob);
  insert into LevelType (LevelType,LevelTypeLong) values
  ("F","Full"),
  ("D","Diff"),
  ("I","Inc");
- Add ACL to restore only to original location.
- Add a recursive mark command (rmark) to restore.
- "Minimum Job Interval = nnn" sets minimum interval between Jobs
  of the same level and does not permit multiple simultaneous
  running of that Job (i.e. lets any previous invocation finish
  before doing Interval testing).
- Look at simplifying File exclusions.
- Fix store_yesno to be store_bitmask.
- New directive "Delete purged Volumes"
- new pool XXX with ScratchPoolId = MyScratchPool's PoolId and
  let it fill itself, and RecyclePoolId = XXX's PoolId so I can
  see if it become stable and I just have to supervise
  MyScratchPool
- If I want to remove this pool, I set RecyclePoolId = MyScratchPool's
  PoolId, and when it is empty remove it.
- Figure out how to recycle Scratch volumes back to the Scratch
  Pool.
- Add Volume=SCRTCH
- Allow Check Labels to be used with Bacula labels.
- "Resuming" a failed backup (lost line for example) by using the
  failed backup as a sort of "base" job.
- Look at NDMP
- Email to the user when the tape is about to need changing x
  days before it needs changing.
- Command to show next tape that will be used for a job even
  if the job is not scheduled.
--- create_file.c.orig  Fri Jul  8 12:13:05 2005
+++ create_file.c       Fri Jul  8 12:13:07 2005
@@ -195,6 +195,8 @@
                     attr->ofname, be.strerror());
               return CF_ERROR;
            }
+        } else if(S_ISSOCK(attr->statp.st_mode)) {
+            Dmsg1(200, "Skipping socket: %s\n", attr->ofname);
         } else {          
             Dmsg1(200, "Restore node: %s\n", attr->ofname);
            if (mknod(attr->ofname, attr->statp.st_mode, attr->statp.st_rdev) != 0 && errno != EEXIST) {
- From: Arunav Mandal <amandal@trolltech.com>
  1. When jobs are running and bacula for some reason crashes or if I do a 
  restart it remembers and jobs it was running before it crashed or restarted 
  as of now I loose all jobs if I restart it.

  2. When spooling and in the midway if client is disconnected for instance a 
  laptop bacula completely discard the spool. It will be nice if it can write 
  that spool to tape so there will be some backups for that client if not all.

  3. We have around 150 clients machines it will be nice to have a option to 
  upgrade all the client machines bacula version automatically.

  4. Atleast one connection should be reserved for the bconsole so at heavy load 
  I should connect to the director via bconsole which at sometimes I can't

  5. Another most important feature that is missing, say at 10am I manually 
  started  backup of client abc and it was a full backup since client abc has 
  no backup history and at 10.30am bacula again automatically started backup of 
  client abc as that was in the schedule. So now we have 2 multiple Full 
  backups of the same client and if we again try to start a full backup of 
  client backup abc bacula won't complain. That should be fixed.

- Fix bpipe.c so that it does not modify results pointer.
  ***FIXME*** calling sequence should be changed.
1.xx Major Projects:
#3   Migration (Move, Copy, Archive Jobs)
#7   Single Job Writing to Multiple Storage Devices
- Reserve blocks other restore jobs when first cannot connect
  to SD.
- Add true/false to conf same as yes/no
- For Windows disaster recovery see http://unattended.sf.net/
- regardless of the retention period, Bacula will not prune the
  last Full, Diff, or Inc File data until a month after the
  retention period for the last Full backup that was done.
- update volume=xxx --- add status=Full
- Remove old spool files on startup.
- Exclude SD spool/working directory.
- Refuse to prune last valid Full backup. Same goes for Catalog.
- Python:
  - Make a callback when Rerun failed levels is called.
  - Give Python program access to Scheduled jobs.
  - Add setting Volume State via Python.
  - Python script to save with Python, not save, save with Bacula.
  - Python script to do backup.
  - What events?
  - Change the Priority, Client, Storage, JobStatus (error) 
    at the start of a job.
- Why is SpoolDirectory = /home/bacula/spool;  not reported
  as an error when writing a DVD?
- Make bootstrap file handle multiple MediaTypes (SD)
- Remove all old Device resource code in Dir and code to pass it
  back in SD -- better, rework it to pass back device statistics.
- Check locking of resources -- be sure to lock devices where previously
  resources were locked. 
- The last part is left in the spool dir.


- In restore don't compare byte count on a raw device -- directory
  entry does not contain bytes.
- To mark files as deleted, run essentially a Verify to disk, and
  when a file is found missing (MarkId != JobId), then create
  a new File record with FileIndex == -1. This could be done
  by the FD at the same time as the backup.
=== rate design
  jcr->last_rate
  jcr->last_runtime
  MA = (last_MA * 3 + rate) / 4
  rate = (bytes - last_bytes) / (runtime - last_runtime)
- Max Vols limit in Pool off by one?
- Implement Files/Bytes,... stats for restore job.
- Implement Total Bytes Written, ... for restore job.
- Despool attributes simultaneously with data in a separate
  thread, rejoined at end of data spooling.
- 7. Implement new Console commands to allow offlining/reserving drives,
     and possibly manipulating the autochanger (much asked for).
- Add start/end date editing in messages (%t %T, %e?) ...
- Add ClientDefs similar to JobDefs.
- Print more info when bextract -p accepts a bad block.
- Fix FD JobType to be set before RunBeforeJob in FD.
- Look at adding full Volume and Pool information to a Volume 
  label so that bscan can get *all* the info. 
- If the user puts "Purge Oldest Volume = yes" or "Recycle Oldest Volume = yes"
  and there is only one volume in the pool, refuse to do it -- otherwise
  he fills the Volume, then immediately starts reusing it.
- Implement copies and stripes.
- Add history file to console.
- Each file on tape creates a JobMedia record. Peter has 4 million
  files spread over 10000 tape files and four tapes. A restore takes
  16 hours to build the restore list.
- Add and option to check if the file size changed during backup.
- Make sure SD deletes spool files on error exit.
- Delete old spool files when SD starts.
- When labeling tapes, if you enter 000026, Bacula uses
  the tape index rather than the Volume name 000026.
- Add offline tape command to Bacula console.
- Bug: 
  Enter MediaId or Volume name: 32
  Enter new Volume name: DLT-20Dec04
  Automatically selected Pool: Default
  Connecting to Storage daemon DLTDrive at 192.168.68.104:9103 ...
  Sending relabel command from "DLT-28Jun03" to "DLT-20Dec04" ...
  block.c:552 Write error at 0:0 on device /dev/nst0. ERR=Bad file descriptor.
  Error writing final EOF to tape. This tape may not be readable.
  dev.c:1207 ioctl MTWEOF error on /dev/nst0. ERR=Permission denied.
  askdir.c:219 NULL Volume name. This shouldn't happen!!!
  3912 Failed to label Volume: ERR=dev.c:1207 ioctl MTWEOF error on /dev/nst0. ERR=Permission denied.
  Label command failed for Volume DLT-20Dec04.
  Do not forget to mount the drive!!!
- Bug: if a job is manually scheduled to run later, it does not appear
  in any status report and cannot be cancelled.

==== Keeping track of deleted files ====
     My "trick" for keeping track of deletions is the following.
     Assuming the user turns on this option, after all the files
     have been backed up, but before the job has terminated, the
     FD will make a pass through all the files and send their
     names to the DIR (*exactly* the same as what a Verify job
     currently does).  This will probably be done at the same
     time the files are being sent to the SD avoiding a second
     pass.  The DIR will then compare that to what is stored in
     the catalog.  Any files in the catalog but not in what the
     FD sent will receive a catalog File entry that indicates
     that at that point in time the file was deleted.

     During a restore, any file initially picked up by some
     backup (Full, ...) then subsequently having a File entry
     marked "delete" will be removed from the tree, so will not
     be restored.  If a file with the same name is later OK it
     will be inserted in the tree -- this already happens.  All
     will be consistent except for possible changes during the
     running of the FD.

     Since I'm on the subject, some of you may be wondering what
     the utility of the in memory tree is if you are going to
     restore everything (at least it comes up from time to time
     on the list).  Well, it is still *very* useful because it
     allows only the last item found for a particular filename
     (full path) to be entered into the tree, and thus if a file
     is backed up 10 times, only the last copy will be restored.
     I recently (last Friday) restored a complete directory, and
     the Full and all the Differential and Incremental backups
     spanned 3 Volumes.  The first Volume was not even mounted
     because all the files had been updated and hence backed up
     since the Full backup was made.  In this case, the tree
     saved me a *lot* of time.

     Make sure this information is stored on the tape too so
     that it can be restored directly from the tape.

  Comments from Martin Simmons (I think they are all covered):
  Ok, that should cover the basics.  There are few issues though:

  - Restore will depend on the catalog.  I think it is better to include the
  extra data in the backup as well, so it can be seen by bscan and bextract.

  - I'm not sure if it will preserve multiple hard links to the same inode.  Or
  maybe adding or removing links will cause the data to be dumped again?

  - I'm not sure if it will handle renamed directories.  Possibly it will work
  by dumping the whole tree under a renamed directory?

  - It remains to be seen how the backup performance of the DIR's will be
  affected when comparing the catalog for a large filesystem.

=====

Regression tests:
- Add Pool/Storage override regression test.
- Add delete JobId to regression.
- Add a regression test for dbcheck.  
- New test to add bscan to four-concurrent-jobs regression,
  i.e. after the four-concurrent jobs zap the
  database as is done in the bscan-test, then use bscan to
  restore the database, do a restore and compare with the
  original.
- Add restore of specific JobId to regression (item 3
  on the restore prompt)
- Add IPv6 to regression
- Add database test to regression. Test each function like delete,
  purge, ...

- AntiVir can slow down backups on Win32 systems. 
- Win32 systems with FAT32 can be much slower than NTFS for
  more than 1000 files per directory.


1.37 Possibilities:
- A HOLD command to stop all jobs from starting.
- A PAUSE command to pause all running jobs ==> release the
  drive.
- Media Type = LTO,LTO-2,LTO-3
  Media Type Read = LTO,LTO2,LTO3
  Media Type Write = LTO2, LTO3

=== From Carsten Menke <bootsy52@gmx.net>

Following is a list of what I think in the situations where I'm faced with, 
could be a usefull enhancement to bacula, which I'm certain other users will 
benefit from as well.

1. NextJob/NextJobs Directive within a Job Resource in the form of
    NextJobs = job1,job2.

    Why:
    I currently solved the problem with running multiple jobs each after each
    by setting the Max Wait Time for a job to 8 hours, and give
    the jobs different Priorities. However, there scenarios where
    1 Job is directly depending on another job, so if the former job fails,
    the job after it needn't to be run
    while maybe other jobs should run despite of that

Example:
  A Backup Job and a Verify job, if the backup job fails there is no need to run
  the verify job, as the backup job already failed. However, one may like
  to backup the Catalog to disk despite of that the main backup job failed.

Notes:
  I see that this is related to the Event Handlers which are on the ToDo
  list, also it is maybe a good idea to check for the return value and
  execute different actions based on the return value


3. offline capability to bconsole

    Why:
    Currently I use a script which I execute within the last Job via the
    RunAfterJob Directive, to release and eject the tape.
    So I have to call bconsole "release=Storage-Name" and afterwards
    mt -f /dev/nst0 eject to get the tape out.

    If I have multiple Storage Devices, than these may not be /dev/nst0 and
    I have to modify the script or call it with parameters etc.
    This would actually not be needed, as everything is already defined
    in bacula-sd.conf and if   I can invoke bconsole with the
    storage name via $1 in the script than I'm done and information is
    not duplicated.

4. %s for Storage Name added to the chars being substituted in "RunAfterJob"

    Why:

    For the reason mentioned in 3. to have the ability to call a
    script with /scripts/foobar %s and in the script use $1
    to pass the Storage Name to bconsole

5. Setting Volume State within a Job Resource

    Why:
    Instead of using "Maximum Volume Jobs" in the Pool Resource,
    I would have the possibilty to define
    in a Job Resource that after this certain job is run, the Volume State
    should be set to "Volume State = Used", this give more flexibility (IMHO).

6. Localization of Bacula Messages

    Why:
    Unfortunatley many,many people I work with don't speak english very well.
    So if at least the Reporting messages would be localized then they
    would  understand that they have to change the tape,etc. etc.

    I volunteer to do the german translations, and if I can convince my wife also
    french and Morre (western african language).

7. OK, this is evil, probably bound to security risks and maybe not possible
    due to the design of bacula.

    Implementation of Backtics ( `command` ) for shell comand execution to
    the "Label Format" Directive.

Why:

    Currently I have defined BACULA_DAY_OF_WEEK="day1|day2..." resulting in
    Label Format = "HolyBackup-${BACULA_DAY_OF_WEEK[${WeekDay}]}". If I could
    use backticks than I could use "Label Format = HolyBackup-`date +%A` to have
    the localized name for the day of the week appended to the
    format string. Then I have the tape labeled automatically with weekday
    name in the correct language.
==========
-  Yes, that is surely the case. I probably should turn those into Warning
   errors. In addition, you just made me think that it might not be bad to
   add an option to check the file size after backing up the file and
   report if it changes. This would be done as an option because it would
   add extra overhead.
 
   Kern, good idea.  If you do do that, mention in the output: file 
   shrunk, or file expanded, just to make it obvious to the user 
   (without having to the refer to file size), just how the file size 
   changed.
 
   Would this option be for all file, or just one file?  Or a fileset?
- Make output from status use html table tags for nicely 
  presenting in a browser.
- Can one write tapes faster with 8192 byte block sizes?
- Document security problems with the same password for everyone in
  rpm and Win32 releases.
- Browse generations of files.
- I've seen an error when my catalog's File table fills up.  I
   then have to recreate the File table with a larger maximum row
   size.  Relevant information is at
   http://dev.mysql.com/doc/mysql/en/Full_table.html ; I think the
   "Installing and Configuring MySQL" chapter should talk a bit
   about this potential problem, and recommend a solution.
- For Solaris must use POSIX awk.
- Want speed of writing to tape while despooling.
- Supported autochanger:
OS: Linux
Man.: HP
Media: LTO-2
Model: SSL1016
Slots: 16
Cap: 200GB
- Supported drive:
  Wangtek 6525ES (SCSI-1 QIC drive, 525MB), under Linux 2.4.something, 
  bacula 1.36.0/1 works with blocksize 16k INSIDE bacula-sd.conf.
- Add regex from http://www.pcre.org to Bacula for Win32.
- Use only shell tools no make in CDROM package.
- Include within include does it work?
- Implement a Pool of type Cleaning?
- Implement VolReadTime and VolWriteTime in SD
- Modify Backing up Your Database to include a bootstrap file.
- Think about making certain database errors fatal.
- Look at correcting the time jump in the scheduler for daylight
  savings time changes.
- Add a "real" timer to network connections.
- Promote to Full = Time period 
- Check dates entered by user for correctness (month/day/... ranges)
- Compress restore Volume listing by date and first file.
- Look at patches/bacula_db.b2z postgresql that loops during restore.
  See Gregory Wright.
- Perhaps add read/write programs and/or plugins to FileSets.
- How to handle backing up portables ...
- Add some sort of guaranteed Interval for upgrading jobs.
- Can we write the state file after every job terminates? On Win32
  the system crashes and the state file is not updated.
- Limit bandwidth

Documentation to do: (any release a little bit at a time)
- Doc to do unmount before removing magazine.
- Alternative to static linking "ldd prog" save all binaries listed,
  restore them and point LD_LIBRARY_PATH to them.
- Document add "</dev/null >/dev/null 2>&1" to the bacula-fd command line
- Document query file format.
- Add more documentation for bsr files.
- Document problems with Verify and pruning.
- Document how to use multiple databases.
- VXA drives have a "cleaning required"
  indicator, but Exabyte recommends preventive cleaning after every 75
  hours of operation.
  From Phil:
    In this context, it should be noted that Exabyte has a command-line
    vxatool utility available for free download. (The current version is
    vxatool-3.72.) It can get diagnostic info, read, write and erase tapes,
    test the drive, unload tapes, change drive settings, flash new firmware,
    etc.
    Of particular interest in this context is that vxatool <device> -i will
    report, among other details, the time since last cleaning in tape motion
    minutes. This information can be retrieved (and settings changed, for
    that matter) through the generic-SCSI device even when Bacula has the
    regular tape device locked. (Needless to say, I don't recommend
    changing tape settings while a job is running.)
- Lookup HP cleaning recommendations.
- Lookup HP tape replacement recommendations (see trouble shooting autochanger)
- Document doing table repair


===================================
- Add macro expansions in JobDefs.
  Run Before Job = "SomeFile %{Level} %{Client}"
  Write Bootstrap="/some/dir/%{JobName}_%{Client}.bsr"
- Use non-blocking network I/O but if no data is available, use
  select().
- Use gather write() for network I/O.
- Autorestart on crash.
- Add bandwidth limiting.
- Add acks every once and a while from the SD to keep
  the line from timing out.
- When an error in input occurs and conio beeps, you can back
  up through the prompt.
- Detect fixed tape block mode during positioning by looking at
  block numbers in btape "test".  Possibly adjust in Bacula.
- Fix list volumes to output volume retention in some other
  units, perhaps via a directive.
- If opening a tape in read/write mode fails attempt to open
  it in read-only mode, and mark the tape for read only.
- Allow Simultaneous Priorities = yes  => run up to Max concurrent jobs even
  with multiple priorities.
- If you use restore replace=never, the directory attributes for
  non-existent directories will not be restored properly.

- see lzma401.zip in others directory for new compression
  algorithm/library.
- Minimal autochanger handling in Bacula and in btape.
- Look into how tar does not save sockets and the possiblity of
  not saving them in Bacula (Martin Simmons reported this).
- Fix restore jobs so that multiple jobs can run if they
  are not using the same tape(s).
- Allow the user to select JobType for manual pruning/purging.
- bscan does not put first of two volumes back with all info in
  bscan-test.
- Implement the FreeBSD nodump flag in chflags.
- Figure out how to make named console messages go only to that
  console and to the non-restricted console (new console class?).
- Make restricted console prompt for password if *ask* is set or
  perhaps if password is undefined.
- Implement "from ISO-date/time every x hours/days/weeks/months" in
  schedules.

==== from Marc Schoechlin
- the help-command should be more verbose
  (it should explain the paramters of the different 
  commands in detail)
  -> its time-comsuming to consult the manual anytime
     you need a special parameter
  -> maybe its more easy to maintain this, if the
     descriptions of that commands are outsourced to
     a ceratin-file
- the cd-command should allow complete paths
  i.e. cd /foo/bar/foo/bar
  -> if a customer mails me the path to a certain file,
     its faster to enter the specified directory
- if the password is not configured in bconsole.conf
  you should be asked for it.
  -> sometimes you like to do restore on a customer-machine
     which shouldnt know the password for bacula.
  -> adding the password to the file favours admins
     to forget to remove the password after usage
  -> security-aspects
     the protection of that file is less important
- long-listed-output of commands should be scrollable
  like the unix more/less-command does
  -> if someone runs 200 and more machines, the lists could
     be a little long and complex
- command-output should be shown column by column
  to reduce scrolling and to increase clarity
  -> see last item
- lsmark should list the selected files with full
  paths
- wildcards for selecting and file and directories would be nice
- any actions should be interuptable with STRG+C
- command-expansion would be pretty cool
====
- When the replace Never option is set, new directory permissions
  are not restored. See bug 213. To fix this requires creating a
  list of newly restored directories so that those directory 
  permissions *can* be restored.
- Compaction of Disk space by "migrating" Volumes that have pruned
  Jobs (what criteria? size, #jobs, time).
- Add prune all command
- Document fact that purge can destroy a part of a restore by purging
  one volume while others remain valid -- perhaps mark Jobs.
- Add multiple-media-types.txt
- look at mxt-changer.html
- Make ? do a help command (no return needed).
- Implement restore directory.
- Document streams and how to implement them.
- Try not to re-backup a file if a new hard link is added.
- Add feature to backup hard links only, but not the data.
- Fix stream handling to be simpler.
- Add Priority and Bootstrap to Run a Job.
- Eliminate Restore "Run Restore Job" prompt by allowing new "run command
  to be issued"
- Remove View FileSet button from Run a Job dialog.
- Handle prompt for restore job at end of Restore command.
- Add display of total selected files to Restore window.
- Add tree pane to left of window.
- Add progress meter.
- Max wait time or max run time causes seg fault -- see runtime-bug.txt
- Document writing to a CD/DVD with Bacula.
- Add a "base" package to the window installer for pthreadsVCE.dll
  which is needed by all packages.
- Add message to user to check for fixed block size when the forward
  space test fails in btape.
- When unmarking a directory check if all files below are unmarked and
  then remove the + flag -- in the restore tree.
- Possibly implement: Action = Unmount Device="TapeDrive1" in Admin jobs.
- Setup lrrd graphs: (http://www.linpro.no/projects/lrrd/) Mike Acar.
- Revisit the question of multiple Volumes (disk) on a single device.
- Add a block copy option to bcopy.
- Investigate adding Mac Resource Forks.
- Finish work on Gnome restore GUI.
- Fix "llist jobid=xx" where no fileset or client exists.
- For each job type (Admin, Restore, ...) require only the really necessary
  fields.- Pass Director resource name as an option to the Console.
- Add a "batch" mode to the Console (no unsolicited queries, ...).
- Add a .list all files in the restore tree (probably also a list all files)
  Do both a long and short form.
- Allow browsing the catalog to see all versions of a file (with 
  stat data on each file).
- Restore attributes of directory if replace=never set but directory
  did not exist.
- Use SHA1 on authentication if possible.
- See comtest-xxx.zip for Windows code to talk to USB.
- Add John's appended files:
   Appended = {     /files/server/logs/http/*log   }
   and such files would be treated as follows.On a FULL backup, they would
   be backed up like any other file.On an INCREMENTAL backup, where a
   previous INCREMENTAL or FULL was already in thecatalogue and the length
   of the file wasgreater than the length of the last backup, only thedata
   added since the last backup will be dumped.On an INCREMENTAL backup, if
   the length of the file is less than thelength of the file with the same
   name last backed up, the completefile is dumped.On Windows systems, with
   creation date of files, we can be evensmarter about this and not count
   entirely upon the length.On a restore, the full and all incrementals
   since it will beapplied in sequence to restore the file.  
- Check new HAVE_WIN32 open bits.    
- Check if the tape has moved before writing.  
- Handling removable disks -- see below:
- Keep track of tape use time, and report when cleaning is necessary.
- Add FromClient and ToClient keywords on restore command (or
  BackupClient RestoreClient).
- Implement a JobSet, which groups any number of jobs. If the
  JobSet is started, all the jobs are started together.
  Allow Pool, Level, and Schedule overrides.
- Enhance cancel to timeout BSOCK packets after a specific delay.
- Do scheduling by UTC using gmtime_r() in run_conf, scheduler, and   
  ua_status.!!! Thanks to Alan Brown for this tip.
- Look at updating Volume Jobs so that Max Volume Jobs = 1 will work
  correctly for multiple simultaneous jobs.
- Correct code so that FileSet MD5 is calculated for < and | filename   
  generation.
- Implement the Media record flag that indicates that the Volume does disk 
  addressing.
- Implement VolAddr, which is used when Volume is addressed like a disk,
  and form it from VolFile and VolBlock.
- Make multiple restore jobs for multiple media types specifying 
  the proper storage type.
- Fix fast block rejection (stored/read_record.c:118). It passes a null
  pointer (rec) to try_repositioning().
- Look at extracting Win data from BackupRead.
- Implement RestoreJobRetention? Maybe better "JobRetention" in a Job,
  which would take precidence over the Catalog "JobRetention".
- Implement Label Format in Add and Label console commands.
- Possibly up network buffers to 65K. Put on variable.
- Put email tape request delays on one or more variables. User wants
  to cancel the job after a certain time interval.  Maximum Mount Wait?
- Job, Client, Device, Pool, or Volume?
  Is it possible to make this a directive which is *optional* in multiple
  resources, like Level? If so, I think I'd make it an optional directive
  in Job, Client, and Pool, with precedence such that Job overrides Client
  which in turn overrides Pool.

- New Storage specifications:
  - Want to write to multiple storage devices simultaneously
  - Want to write to multiple storage devices sequentially (in one job)
  - Want to read/write simultaneously
  - Key is MediaType -- it must match

  Passed to SD as a sort of BSR record called Storage Specification
    Record or SSR.
    SSR                    
      Next -> Next SSR
      MediaType -> Next MediaType
      Pool -> Next Pool
      Device -> Next Device
  Job Resource
     Allow multiple Storage specifications
     New flags
        One Archive = yes
        One Device = yes
        One Storage = yes
        One MediaType = yes
        One Pool = yes
  Storage
     Allow Multiple Pool specifications (note, Pool currently
       in Job resource).
     Allow Multiple MediaType specifications in Dir conf
     Allow Multiple Device specifications in Dir conf
     Perhaps keep this in a single SSR
  Tie a Volume to a specific device by using a MediaType that 
    is contained in only one device.
  In SD allow Device to have Multiple MediaTypes

- Ideas from Jerry Scharf:
  First let's point out some big pluses that bacula has for this
        it's open source
        more importantly it's active. Thank you so much for that
        even more important, it's not flaky
        it has an open access catalog, opening many possibilities
        it's pushing toward heterogeneous systems capability
  big things:
   Macintosh file client
        macs are an interesting niche, but I fear a server is a rathole
   working bare iron recovery for windows
   the option for  inc/diff backups not reset on fileset revision
        a) use both change and inode update time against base time
        b) do the full catalog check (expensive but accurate)
   sizing guide (how much system is needed to back up N systems/files)
   consultants on using bacula in building a disaster recovery system
   an integration guide
        or how to get at fancy things that one could do with bacula
   logwatch code for bacula logs (or similar)
   linux distro inclusion of bacula (brings good and bad, but necessary)
   win2k/XP server capability (icky but you asked)
   support for Oracle database ??
===
- Look at adding SQL server and Exchange support for Windows. 
- Make dev->file and dev->block_num signed integers so that -1 can
  be an invalid value which happens with BSR.
- Create VolAddr for disk files in place of VolFile and VolBlock. This
  is needed to properly specify ranges.
- Add progress of files/bytes to SD and FD.
- Print warning message if FileId > 4 billion
- do a "messages" before the first prompt in Console
- Client does not show busy during Estimate command.
- Implement Console mtx commands.
- Implement a Mount Command and an Unmount Command where
  the users could specify a system command to be performed
  to do the mount, after which Bacula could attempt to
  read the device. This is for Removeable media such as a CDROM.
  - Most likely, this mount command would be invoked explicitly
  by the user using the current Console "mount" and "unmount" 
  commands -- the Storage Daemon would do the right thing 
  depending on the exact nature of the device.
  - As with tape drives, when Bacula wanted a new removable
  disk mounted, it would unmount the old one, and send a message
  to the user, who would then use "mount" as described above 
  once he had actually inserted the disk.
- Implement dump/print label to UA
- Spool to disk only when the tape is full, then when a tape is hung move
  it to tape.
- bextract is sending everything to the log file ****FIXME****
- Allow multiple Storage specifications (or multiple names on
  a single Storage specification) in the Job record. Thus a job 
  can be backed up to a number of storage devices.
- Implement some way for the File daemon to contact the Director 
  to start a job or pass its DHCP obtained IP number.
- Implement a query tape prompt/replace feature for a console
- Copy console @ code to gnome2-console
- Make AES the only encryption algorithm see 
  http://csrc.nist.gov/CryptoToolkit/aes/).  It's
  an officially adopted standard, has survived peer
  review, and provides keys up to 256 bits.
- Take a careful look at SetACL http://setacl.sourceforge.net     
- Make tree walk routines like cd, ls, ... more user friendly
  by handling spaces better.
- Make sure that Bacula rechecks the tape after the 20 min wait.
- Set IO_NOWAIT on Bacula TCP/IP packets.
- Try doing a raw partition backup and restore by mounting a
  Windows partition.
- From Lars Kellers:
    Yes, it would allow to highly automatic the request for new tapes. If a 
    tape is empty, bacula reads the barcodes (native or simulated), and if 
    an unused tape is found, it runs the label command with all the 
    necessary parameters.

    By the way can bacula automatically "move" an empty/purged volume say 
    in the "short" pool to the "long" pool if this pool runs out of volume 
    space?
- What to do about "list files job=xxx".
- Get and test MySQL 4.0
- Look at how fuser works and /proc/PID/fd that is how Nic found the
  file descriptor leak in Bacula.
- Implement WrapCounters in Counters.
- Add heartbeat from FD to SD if hb interval expires.
- Can we dynamically change FileSets?
- If pool specified to label command and Label Format is specified,
  automatically generate the Volume name.
- Why can't SQL do the filename sort for restore?
- Add ExhautiveRestoreSearch
- Look at the possibility of loading only the necessary 
  data into the restore tree (i.e. do it one directory at a
  time as the user walks through the tree).
- Possibly use the hash code if the user selects all for a restore command.
- Fix "restore all" to bypass building the tree.
- Prohibit backing up archive device (findlib/find_one.c:128)
- Implement Release Device in the Job resource to unmount a drive.
- Implement Acquire Device in the Job resource to mount a drive,
  be sure this works with admin jobs so that the user can get
  prompted to insert the correct tape.  Possibly some way to say to
  run the job but don't save the files.
- Make things like list where a file is saved case independent for
  Windows.
- Implement migrate
- Use autochanger to handle multiple devices.
- On Windows with very long path names, it may be impossible to create 
  a file (and thus restore it) because the total length is too long.
  We must cd into the directory then create the file without the
  full path name.
- Implement a Recycle command
- Test a second language e.g. french.
- Start working on Base jobs.
- Implement UnsavedFiles DB record.
- From Phil Stracchino:
  It would probably be a per-client option, and would be called
  something like, say, "Automatically purge obsoleted jobs".  What it
  would do is, when you successfully complete a Differential backup of a
  client, it would automatically purge all Incremental backups for that
  client that are rendered redundant by that Differential.  Likewise,
  when a Full backup on a client completed, it would automatically purge
  all Differential and Incremental jobs obsoleted by that Full backup.
  This would let people minimize the number of tapes they're keeping on
  hand without having to master the art of retention times.
- When doing a Backup send all attributes back to the Director, who
  would then figure out what files have been deleted.
- Currently in mount.c:236 the SD simply creates a Volume. It should have
  explicit permission to do so.  It should also mark the tape in error
  if there is an error.
- Cancel waiting for Client connect in SD if FD goes away.

- Implement timeout in response() when it should come quickly.
- Implement a Slot priority (loaded/not loaded).
- Implement "vacation" Incremental only saves.
- Implement create "FileSet"?
- Add prefixlinks to where or not where absolute links to FD.
- Issue message to mount a new tape before the rewind.
- Simplified client job initiation for portables.
- If SD cannot open a drive, make it periodically retry.
- Add more of the config info to the tape label.

- If tape is marked read-only, then try opening it read-only rather than
  failing, and remember that it cannot be written.
- Refine SD waiting output:
    Device is being positioned
    >     Device is being positioned for append
    >     Device is being positioned to file x
    > 
- Figure out some way to estimate output size and to avoid splitting
  a backup across two Volumes -- this could be useful for writing CDROMs
  where you really prefer not to have it split -- not serious.
- Have SD compute MD5 or SHA1 and compare to what FD computes.
- Make VolumeToCatalog calculate an MD5 or SHA1 from the 
  actual data on the Volume and compare it.                  
- Implement Bacula plugins -- design API
- Make bcopy read through bad tape records.
- Program files (i.e. execute a program to read/write files).
  Pass read date of last backup, size of file last time.
- Add Signature type to File DB record.
- CD into subdirectory when open()ing files for backup to
  speed up things.  Test with testfind().
- Priority job to go to top of list.
- Why are save/restore of device different sizes (sparse?)   Yup! Fix it.
- Implement some way for the Console to dynamically create a job.
- Solaris -I on tar for include list
- Need a verbose mode in restore, perhaps to bsr.
- bscan without -v is too quiet -- perhaps show jobs.
- Add code to reject whole blocks if not wanted on restore.
- Check if we can increase Bacula FD priorty in Win2000
- Make sure the MaxVolFiles is fully implemented in SD
- Check if both CatalogFiles and UseCatalog are set to SD.
- Possibly add email to Watchdog if drive is unmounted too
  long and a job is waiting on the drive.
- After unmount, if restore job started, ask to mount.
- Add UA rc and history files.
- put termcap (used by console) in ./configure and
  allow -with-termcap-dir.
- Fix Autoprune for Volumes to respect need for full save.
- Compare tape to Client files (attributes, or attributes and data) 
- Make all database Ids 64 bit.
- Allow console commands to detach or run in background.
- Fix status delay on storage daemon during rewind.
- Add SD message variables to control operator wait time
  - Maximum Operator Wait
  - Minimum Message Interval
  - Maximum Message Interval
- Send Operator message when cannot read tape label.
- Verify level=Volume (scan only), level=Data (compare of data to file).
  Verify level=Catalog, level=InitCatalog
- Events file
- Add keyword search to show command in Console.
- Events : tape has more than xxx bytes.
- Complete code in Bacula Resources -- this will permit
  reading a new config file at any time.
- Handle ctl-c in Console
- Implement script driven addition of File daemon to config files.
- Think about how to make Bacula work better with File (non-tape) archives.
- Write Unix emulator for Windows.
- Put memory utilization in Status output of each daemon
  if full status requested or if some level of debug on.
- Make database type selectable by .conf files i.e. at runtime
- Set flag for uname -a.  Add to Volume label.
- Restore files modified after date
- SET LD_RUN_PATH=$HOME/mysql/lib/mysql
- Remove duplicate fields from jcr (e.g. jcr.level and jcr.jr.Level, ...).
- Timout a job or terminate if link goes down, or reopen link and query.
- Concept of precious tapes (cannot be reused).
- Make bcopy copy with a single tape drive.
- Permit changing ownership during restore.

- From Phil:
  > My suggestion:  Add a feature on the systray menu-icon menu to request
  > an immediate backup now.  This would be useful for laptop users who may
  > not be on the network when the regular scheduled backup is run.
  > 
  > My wife's suggestion: Add a setting to the win32 client to allow it to
  > shut down the machine after backup is complete (after, of course,
  > displaying a "System will shut down in one minute, click here to cancel"
  > warning dialog).  This would be useful for sites that want user
  > woorkstations to be shut down overnight to save power.
  > 

- Autolabel should be specified by DIR instead of SD.
- Storage daemon    
  - Add media capacity
  - AutoScan (check checksum of tape)
  - Format command = "format /dev/nst0"
  - MaxRewindTime
  - MinRewindTime
  - MaxBufferSize
  - Seek resolution (usually corresponds to buffer size)
  - EODErrorCode=ENOSPC or code
  - Partial Read error code
  - Partial write error code
  - Nonformatted read error
  - Nonformatted write error
  - WriteProtected error
  - IOTimeout
  - OpenRetries
  - OpenTimeout
  - IgnoreCloseErrors=yes
  - Tape=yes
  - NoRewind=yes
- Pool
  - Maxwrites
  - Recycle period
- Job
  - MaxWarnings
  - MaxErrors (job?)
=====
- FD sends unsaved file list to Director at end of job (see
  RFC below).
- File daemon should build list of files skipped, and then
  at end of save retry and report any errors.
- Write a Storage daemon that uses pipes and
  standard Unix programs to write to the tape.
  See afbackup.
- Need something that monitors the JCR queue and
  times out jobs by asking the deamons where they are.
- Enhance Jmsg code to permit buffering and saving to disk.
- device driver = "xxxx" for drives.
- Verify from Volume
- Ensure that /dev/null works
- Need report class for messages. Perhaps
  report resource where report=group of messages
- enhance scan_attrib and rename scan_jobtype, and
  fill in code for "since" option 
- Director needs a time after which the report status is sent
  anyway -- or better yet, a retry time for the job.
- Don't reschedule a job if previous incarnation is still running.
- Some way to automatically backup everything is needed????
- Need a structure for pending actions:
  - buffered messages
  - termination status (part of buffered msgs?)
- Drive management
  Read, Write, Clean, Delete
- Login to Bacula; Bacula users with different permissions:
   owner, group, user, quotas
- Store info on each file system type (probably in the job header on tape.
  This could be the output of df; or perhaps some sort of /etc/mtab record.

========= ideas ===============
From: "Jerry K. Schieffer" <jerry@skylinetechnology.com>
To: <kern@sibbald.com>
Subject: RE: [Bacula-users] future large programming jobs
Date: Thu, 26 Feb 2004 11:34:54 -0600

I noticed the subject thread and thought I would offer the following
merely as sources of ideas, i.e. something to think about, not even as
strong as a request.  In my former life (before retiring) I often
dealt with backups and storage management issues/products as a
developer and as a consultant.  I am currently migrating my personal
network from amanda to bacula specifically because of the ability to
cross media boundaries during storing backups.
Are you familiar with the commercial product called ADSM (I think IBM
now sells it under the Tivoli label)?  It has a couple of interesting
ideas that may apply to the following topics.

1. Migration:  Consider that when you need to restore a system, there
may be pressure to hurry.  If all the information for a single client
can eventually end up on the same media (and in chronological order),
the restore is facillitated by not having to search past information
from other clients.  ADSM has the concept of "client affinity" that
may be associated with it's storage pools.  It seems to me that this
concept (as an optional feature) might fit in your architecture for
migration.

ADSM also has the concept of defining one or more storage pools as
"copy pools" (almost mirrors, but only in the sense of contents).
These pools provide the ability to have duplicte data stored both
onsite and offsite.  The copy process can be scheduled to be handled
by their storage manager during periods when there is no backup
activity.  Again, the migration process might be a place to consider
implementing something like this.

>
> It strikes me that it would be very nice to be able to do things
like
> have the Job(s) backing up the machines run, and once they have all
> completed, start a migration job to copy the data from disks Volumes
to
> a tape library and then to offsite storage. Maybe this can already
be
> done with some careful scheduling and Job prioritzation; the events
> mechanism described below would probably make it very easy.

This is the goal. In the first step (before events), you simply
schedule
the Migration to tape later.

2. Base jobs:  In ADSM, each copy of each stored file is tracked in
the database.  Once a file (unique by path and metadata such as dates,
size, ownership, etc.) is in a copy pool, no more copies are made.  In
other words, when you start ADSM, it begins like your concept of a
base job.  After that it is in the "incremental" mode.  You can
configure the number of "generations" of files to be retained, plus a
retention date after which even old generations are purged.  The
database tracks the contents of media and projects the percentage of
each volume that is valid.  When the valid content of a volume drops
below a configured percentage, the valid data are migrated to another
volume and the old volume is marked as empty.  Note, this requires
ADSM to have an idea of the contents of a client, i.e. marking the
database when an existing file was deleted, but this would solve your
issue of restoring a client without restoring deleted files.

This is pretty far from what bacula now does, but if you are going to
rip things up for Base jobs,.....
Also, the benefits of this are huge for very large shops, especially
with media robots, but are a pain for shops with manual media
mounting.

>
> Base jobs sound pretty useful, but I'm not dying for them.

Nobody is dying for them, but when you see what it does, you will die
without it.

3. Restoring deleted files:  Since I think my comments in (2) above
have low probability of implementation, I'll also suggest that you
could approach the issue of deleted files by a mechanism of having the
fd report to the dir, a list of all files on the client for every
backup job.  The dir could note in the database entry for each file
the date that the file was seen.  Then if a restore as of date X takes
place, only files that exist from before X until after X would be
restored.  Probably the major cost here is the extra date container in
each row of the files table.

Thanks for "listening".  I hope some of this helps.  If you want to
contact me, please send me an email - I read some but not all of the
mailing list traffic and might miss a reply there.

Please accept my compliments for bacula.  It is doing a great job for
me!!  I sympathize with you in the need to wrestle with excelence in
execution vs. excelence in feature inclusion.

Regards,
Jerry Schieffer

==============================

Longer term to do:
- Design at hierarchial storage for Bacula. Migration and Clone. 
- Implement FSM (File System Modules).
- Audit M_ error codes to ensure they are correct and consistent.
- Add variable break characters to lex analyzer.
  Either a bit mask or a string of chars so that
  the caller can change the break characters.
- Make a single T_BREAK to replace T_COMMA, etc.
- Ensure that File daemon and Storage daemon can
  continue a save if the Director goes down (this
  is NOT currently the case). Must detect socket error,
  buffer messages for later. 
- Enhance time/duration input to allow multiple qualifiers e.g. 3d2h
- Add ability to backup to two Storage devices (two SD sessions) at
  the same time -- e.g. onsite, offsite.
- Add the ability to consolidate old backup sets (basically do a restore
  to tape and appropriately update the catalog). Compress Volume sets.
  Might need to spool via file is only one drive is available.
- Compress or consolidate Volumes of old possibly deleted files. Perhaps
  someway to do so with every volume that has less than x% valid 
  files.


Migration: Move a backup from one Volume to another
Clone:     Copy a backup -- two Volumes

Bacula Migration is based on Jobs (apparently Networker is file by file).

Migration triggered by:
  Number of Jobs
  Number of Volumes
  Age of Jobs
  Highwater mark (keep total size)
  Lowwater mark
  


======================================================
        Base Jobs design
It is somewhat like a Full save becomes an incremental since
the Base job (or jobs) plus other non-base files.
Need:
- A Base backup is same as Full backup, just different type.
- New BaseFiles table that contains:
    BaseId - index
    BaseJobId - Base JobId referenced for this FileId (needed ???)
    JobId - JobId currently running
    FileId - File not backed up, exists in Base Job
    FileIndex - FileIndex from Base Job.
  i.e. for each base file that exists but is not saved because
  it has not changed, the File daemon sends the JobId, BaseId,
  FileId, FileIndex back to the Director who creates the DB entry.
- To initiate a Base save, the Director sends the FD 
  the FileId, and full filename for each file in the Base.
- When the FD finds a Base file, he requests the Director to
  send him the full File entry (stat packet plus MD5), or
  conversely, the FD sends it to the Director and the Director
  says yes or no. This can be quite rapid if the FileId is kept
  by the FD for each Base Filename.          
- It is probably better to have the comparison done by the FD
  despite the fact that the File entry must be sent across the
  network.
- An alternative would be to send the FD the whole File entry
  from the start. The disadvantage is that it requires a lot of
  space. The advantage is that it requires less communications
  during the save.
- The Job record must be updated to indicate that one or more
  Bases were used.
- At end of Job, FD returns:   
   1. Count of base files/bytes not written to tape (i.e. matches)
   2. Count of base file that were saved i.e. had changed.
- No tape record would be written for a Base file that matches, in the
  same way that no tape record is written for Incremental jobs where
  the file is not saved because it is unchanged.
- On a restore, all the Base file records must explicitly be
  found from the BaseFile tape. I.e. for each Full save that is marked
  to have one or more Base Jobs, search the BaseFile for all occurrences
  of JobId.
- An optimization might be to make the BaseFile have:
     JobId
     BaseId
     FileId
  plus
     FileIndex
  This would avoid the need to explicitly fetch each File record for
  the Base job.  The Base Job record will be fetched to get the
  VolSessionId and VolSessionTime.
=========================================================  


========================================================== 
    Unsaved File design
For each Incremental job that is run, there may be files that
were found but not saved because they were locked (this applies
only to Windows). Such a system could send back to the Director
a list of Unsaved files.
Need:
- New UnSavedFiles table that contains:
  JobId
  PathId
  FilenameId
- Then in the next Incremental job, the list of Unsaved Files will be
  feed to the FD, who will ensure that they are explicitly chosen even
  if standard date/time check would not have selected them.
=============================================================


=====
   Multiple drive autochanger data:  see Alan Brown
   mtx -f xxx unloadStorage Element 1 is Already Full(drive 0 was empty)
   Unloading Data Transfer Element into Storage Element 1...source Element 
   Address 480 is Empty

   (drive 0 was empty and so was slot 1)
   >   mtx -f xxx load 15 0
   no response, just returns to the command prompt when complete.
   >   mtx -f xxx status  Storage Changer /dev/changer:2 Drives, 60 Slots ( 2 Import/Export )
   Data Transfer Element 0:Full (Storage Element 15 Loaded):VolumeTag = HX001
   Data Transfer Element 1:Empty
         Storage Element 1:Empty
         Storage Element 2:Full :VolumeTag=HX002
         Storage Element 3:Full :VolumeTag=HX003
         Storage Element 4:Full :VolumeTag=HX004
         Storage Element 5:Full :VolumeTag=HX005
         Storage Element 6:Full :VolumeTag=HX006
         Storage Element 7:Full :VolumeTag=HX007
         Storage Element 8:Full :VolumeTag=HX008
         Storage Element 9:Full :VolumeTag=HX009
         Storage Element 10:Full :VolumeTag=HX010
         Storage Element 11:Empty
         Storage Element 12:Empty
         Storage Element 13:Empty
         Storage Element 14:Empty
         Storage Element 15:Empty
         Storage Element 16:Empty....
         Storage Element 28:Empty
         Storage Element 29:Full :VolumeTag=CLNU01L1
         Storage Element 30:Empty....
         Storage Element 57:Empty
         Storage Element 58:Full :VolumeTag=NEX261L2
         Storage Element 59 IMPORT/EXPORT:Empty
         Storage Element 60 IMPORT/EXPORT:Empty
   $  mtx -f xxx unload
   Unloading Data Transfer Element into Storage Element 15...done

   (just to verify it remembers where it came from, however it can be
    overrriden with mtx unload {slotnumber} to go to any storage slot.)
   Configuration wise:
   There needs to be a table of drive # to devices somewhere - If there are
   multiple changers or drives there may not be a 1:1 correspondance between
   changer drive number and system device name - and depending on the way the
   drives are hooked up to scsi busses, they may not be linearly numbered
   from an offset point either.something like 

   Autochanger drives = 2
   Autochanger drive 0 = /dev/nst1
   Autochanger drive 1 = /dev/nst2
   IMHO, it would be _safest_ to use explicit mtx unload commands at all
   times, not just for multidrive changers. For a 1 drive changer, that's
   just:

   mtx load xx 0
   mtx unload xx 0

   MTX's manpage (1.2.15):
         unload [<slotnum>] [ <drivenum> ]
                    Unloads media from drive  <drivenum>  into  slot
                    <slotnum>. If <drivenum> is omitted, defaults to
                    drive 0 (as do all commands).  If  <slotnum>  is
                    omitted, defaults to the slot that the drive was
                    loaded from. Note that there's currently no  way
                    to  say  'unload  drive 1's media to the slot it
                    came from', other than to  explicitly  use  that
                    slot number as the destination.AB
====

====
SCSI info:
FreeBSD
undef# camcontrol devlist
<WANGTEK 51000  SCSI M74H 12B3>    at scbus0 target 2 lun 0 (pass0,sa0)
<ARCHIVE 4586XX 28887-XXX 4BGD>    at scbus0 target 4 lun 0 (pass1,sa1)
<ARCHIVE 4586XX 28887-XXX 4BGD>    at scbus0 target 4 lun 1 (pass2)

tapeinfo -f /dev/sg0 with a bad tape in drive 1:
[kern@rufus mtx-1.2.17kes]$ ./tapeinfo -f /dev/sg0
Product Type: Tape Drive
Vendor ID: 'HP      '
Product ID: 'C5713A          '
Revision: 'H107'
Attached Changer: No
TapeAlert[3]:   Hard Error: Uncorrectable read/write error.
TapeAlert[20]:    Clean Now: The tape drive neads cleaning NOW.
MinBlock:1
MaxBlock:16777215
SCSI ID: 5
SCSI LUN: 0
Ready: yes
BufferedMode: yes
Medium Type: Not Loaded
Density Code: 0x26
BlockSize: 0
DataCompEnabled: yes
DataCompCapable: yes
DataDeCompEnabled: yes
CompType: 0x20
DeCompType: 0x0
Block Position: 0
=====

====
   Handling removable disks

   From: Karl Cunningham <karlc@keckec.com>

   My backups are only to hard disk these days, in removable bays. This is my
   idea of how a backup to hard disk would work more smoothly. Some of these
   things Bacula does already, but I mention them for completeness. If others
   have better ways to do this, I'd like to hear about it.

   1. Accommodate several disks, rotated similar to how tapes are.  Identified
   by partition volume ID or perhaps by the name of a subdirectory.
   2. Abort & notify the admin if the wrong disk is in the bay.
   3. Write backups to different subdirectories for each machine to be backed
   up.
   4. Volumes (files) get created as needed in the proper subdirectory, one
   for each backup.
   5. When a disk is recycled, remove or zero all old backup files. This is
   important as the disk being recycled may be close to full. This may be
   better done manually since the backup files for many machines may be
   scattered in many subdirectories.
====


=== Done
- Make sure that all do_prompt() calls in Dir check for
  -1 (error) and -2 (cancel) returns.
- Fix foreach_jcr() to have free_jcr() inside next().
  jcr=jcr_walk_start();
  for ( ; jcr; (jcr=jcr_walk_next(jcr)) )
  ...
  jcr_walk_end(jcr);
- A Volume taken from Scratch should take on the retention period
  of the new pool.
- Correct doc for Maximum Changer Wait (and others) accepting only
  integers.
- Implement status that shows why a job is being held in reserve, or
  rather why none of the drives are suitable.
- Implement a way to disable a drive (so you can use the second
  drive of an autochanger, and the first one will not be used or
  even defined).
- Make sure Maximum Volumes is respected in Pools when adding
  Volumes (e.g. when pulling a Scratch volume).