4 \section*{Testing Your Tape Drive With Bacula}
5 \label{_ChapterStart27}
6 \index[general]{Testing Your Tape Drive With Bacula}
7 \addcontentsline{toc}{section}{Testing Your Tape Drive With Bacula}
9 This chapter is concerned with testing and configuring your tape drive to make
10 sure that it will work properly with Bacula using the {\bf btape} program.
13 \subsection*{Summary of Steps to Take to Get Your Tape Drive Working}
14 \index[general]{Working!Summary of Steps to Take to Get Your Tape Drive}
15 \index[general]{Summary of Steps to Take to Get Your Tape Drive Working}
16 \addcontentsline{toc}{subsection}{Summary of Steps to Take to Get Your Tape
19 In general, you should follow the following steps to get your tape drive to
20 work with Bacula. Start with a tape mounted in your drive. If you have an
21 autochanger, load a tape into the drive. We use {\bf /dev/nst0} as the tape
22 drive name, you will need to adapt it according to your system.
24 Do not proceed to the next item until you have succeeded with the previous
28 \item Use tar to write to, then read from your drive:
32 mt -f /dev/nst0 rewind
34 mt -f /dev/nst0 rewind
40 \item Make sure you have a valid and correct Device resource corresponding to
41 your drive. For Linux users, generally, the default one works. For FreeBSD
42 users, there are two possible Device configurations (see below).
44 \item Run the btape {\bf test} command:
48 ./btape -c bacula-sd.conf /dev/nst0
54 It isn't necessary to run the autochanger part of the test at this time, but
55 do not go past this point until the basic test succeeds. If you do have
56 an autochanger, please be sure to read the
57 \ilink{Autochanger chapter}{_ChapterStart18} of this manual.
59 \item Run the btape {\bf fill} command, preferably with two volumes. This
60 can take a long time. If you have an autochanger and it is configured, Bacula
61 will automatically use it. If you do not have it configured, you can manually
62 issue the appropriate {\bf mtx} command, or press the autochanger buttons to
63 change the tape when requested to do so.
65 \item FreeBSD users, if you have a pre-5.0 system run the {\bf tapetest}
66 program, and make sure your system is patched if necessary. The tapetest
67 program can be found in the platform/freebsd directory. The instructions
68 for its use are at the top of the file.
70 \item Run Bacula, and backup a reasonably small directory, say 60 Megabytes.
71 Do three successive backups of this directory.
73 \item Stop Bacula, then restart it. Do another full backup of the same
74 directory. Then stop and restart Bacula.
76 \item Do a restore of the directory backed up, by entering the following
77 restore command, being careful to restore it to an alternate location:
81 restore select all done
87 Do a {\bf diff} on the restored directory to ensure it is identical to the
88 original directory. If you are going to backup multiple different systems
89 (Linux, Windows, Mac, Solaris, FreeBSD, ...), be sure you test the restore
92 \item If you have an autochanger, you should now go back to the btape program
93 and run the autochanger test:
97 ./btape -c bacula-sd.conf /dev/nst0
103 Adjust your autochanger as necessary to ensure that it works correctly. See
104 the Autochanger chapter of this manual for a complete discussion of testing
108 If you have reached this point, you stand a good chance of having everything
109 work. If you get into trouble at any point, {\bf carefully} read the
110 documentation given below. If you cannot get past some point, ask the {\bf
111 bacula-users} email list, but specify which of the steps you have successfully
112 completed. In particular, you may want to look at the
113 \ilink{ Tips for Resolving Problems}{problems1} section below.
115 \label{NoTapeInDrive}
116 \subsubsection*{Problems When no Tape in Drive}
117 \index[general]{Problems When no Tape in Drive}
118 \addcontentsline{toc}{subsubsection}{Problems When no Tape in Drive}
119 When Bacula was first written the Linux 2.4 kernel permitted opening the
120 drive whether or not there was a tape in the drive. Thus the Bacula code is
121 based on the concept that if the drive cannot be opened, there is a serious
122 problem, and the job is failed.
124 With version 2.6 of the Linux kernel, if there is no tape in the drive, the
125 OS will wait two minutes (default) and then return a failure, and consequently,
126 Bacula version 1.36 and below will fail the job. This is important to keep
127 in mind, because if you use an option such as {\bf Offline on Unmount =
128 yes}, there will be a point when there is no tape in the drive, and if
129 another job starts or if Bacula asks the operator to mount a tape, when
130 Bacula attempts to open the drive (about a 20 minute delay), it will fail
131 and Bacula will fail the job.
133 In version 1.38.x, the Bacula code partially gets around this problem -- at
134 least in the initial open of the drive. However, functions like Polling
135 the drive do not work correctly if there is no tape in the drive.
136 Providing you do not use {\bf Offline on Unmount = yes}, you should not
137 experience job failures as mentioned above. If you do experience such
138 failures, you can also increase the {\bf Maximum Open Wait} time interval,
139 which will give you more time to mount the next tape before the job is
142 \subsubsection*{Specifying the Configuration File}
143 \index[general]{File!Specifying the Configuration}
144 \index[general]{Specifying the Configuration File}
145 \addcontentsline{toc}{subsubsection}{Specifying the Configuration File}
147 Starting with version 1.27, each of the tape utility programs including the
148 {\bf btape} program requires a valid Storage daemon configuration file
149 (actually, the only part of the configuration file that {\bf btape} needs is
150 the {\bf Device} resource definitions). This permits {\bf btape} to find the
151 configuration parameters for your archive device (generally a tape drive).
152 Without those parameters, the testing and utility programs do not know how to
153 properly read and write your drive. By default, they use {\bf bacula-sd.conf}
154 in the current directory, but you may specify a different configuration file
155 using the {\bf -c} option.
157 \subsubsection*{Specifying a Device Name For a Tape}
158 \index[general]{Tape!Specifying a Device Name For a}
159 \index[general]{Specifying a Device Name For a Tape}
160 \addcontentsline{toc}{subsubsection}{Specifying a Device Name For a Tape}
162 {\bf btape} {\bf device-name} where the Volume can be found. In the case of a
163 tape, this is the physical device name such as {\bf /dev/nst0} or {\bf
164 /dev/rmt/0ubn} depending on your system that you specify on the Archive Device
165 directive. For the program to work, it must find the identical name in the
166 Device resource of the configuration file. If the name is not found in the
167 list of physical names, the utility program will compare the name you entered
168 to the Device names (rather than the Archive device names).
170 When specifying a tape device, it is preferable that the "non-rewind"
171 variant of the device file name be given. In addition, on systems such as
172 Sun, which have multiple tape access methods, you must be sure to specify
173 to use Berkeley I/O conventions with the device. The
174 {\bf b} in the Solaris (Sun) archive specification {\bf /dev/rmt/0mbn} is
175 what is needed in this case. Bacula does not support SysV tape drive
178 See below for specifying Volume names.
180 \subsubsection*{Specifying a Device Name For a File}
181 \index[general]{File!Specifying a Device Name For a}
182 \index[general]{Specifying a Device Name For a File}
183 \addcontentsline{toc}{subsubsection}{Specifying a Device Name For a File}
185 If you are attempting to read or write an archive file rather than a tape, the
186 {\bf device-name} should be the full path to the archive location including
187 the filename. The filename (last part of the specification) will be stripped
188 and used as the Volume name, and the path (first part before the filename)
189 must have the same entry in the configuration file. So, the path is equivalent
190 to the archive device name, and the filename is equivalent to the volume name.
195 \index[general]{Btape}
196 \addcontentsline{toc}{subsection}{btape}
198 This program permits a number of elementary tape operations via a tty command
199 interface. The {\bf test} command, described below, can be very useful for
200 testing tape drive compatibility problems. Aside from initial testing of tape
201 drive compatibility with {\bf Bacula}, {\bf btape} will be mostly used by
202 developers writing new tape drivers.
204 {\bf btape} can be dangerous to use with existing {\bf Bacula} tapes because
205 it will relabel a tape or write on the tape if so requested regardless of
206 whether or not the tape contains valuable data, so please be careful and use
207 it only on blank tapes.
209 To work properly, {\bf btape} needs to read the Storage daemon's configuration
210 file. As a default, it will look for {\bf bacula-sd.conf} in the current
211 directory. If your configuration file is elsewhere, please use the {\bf -c}
212 option to specify where.
214 The physical device name or the Device resource name must be specified on the
215 command line, and this same device name must be present in the Storage
216 daemon's configuration file read by {\bf btape}
220 Usage: btape [options] device_name
221 -b <file> specify bootstrap file
222 -c <file> set configuration file to file
223 -d <nn> set debug level to nn
224 -p proceed inspite of I/O errors
227 -? print this message.
231 \subsubsection*{Using btape to Verify your Tape Drive}
232 \index[general]{Using btape to Verify your Tape Drive}
233 \index[general]{Drive!Using btape to Verify your Tape}
234 \addcontentsline{toc}{subsubsection}{Using btape to Verify your Tape Drive}
236 An important reason for this program is to ensure that a Storage daemon
237 configuration file is defined so that Bacula will correctly read and write
240 It is highly recommended that you run the {\bf test} command before running
241 your first Bacula job to ensure that the parameters you have defined for your
242 storage device (tape drive) will permit {\bf Bacula} to function properly. You
243 only need to mount a blank tape, enter the command, and the output should be
244 reasonably self explanatory. For example:
248 (ensure that Bacula is not running)
249 ./btape -c /usr/bin/bacula/bacula-sd.conf /dev/nst0
257 Tape block granularity is 1024 bytes.
258 btape: btape.c:376 Using device: /dev/nst0
263 Enter the test command:
271 The output produced should be something similar to the following: I've cut the
272 listing short because it is frequently updated to have new tests.
276 === Append files test ===
277 This test is essential to Bacula.
278 I'm going to write one record in file 0,
279 two records in file 1,
280 and three records in file 2
281 btape: btape.c:387 Rewound /dev/nst0
282 btape: btape.c:855 Wrote one record of 64412 bytes.
283 btape: btape.c:857 Wrote block to device.
284 btape: btape.c:410 Wrote EOF to /dev/nst0
285 btape: btape.c:855 Wrote one record of 64412 bytes.
286 btape: btape.c:857 Wrote block to device.
287 btape: btape.c:855 Wrote one record of 64412 bytes.
288 btape: btape.c:857 Wrote block to device.
289 btape: btape.c:410 Wrote EOF to /dev/nst0
290 btape: btape.c:855 Wrote one record of 64412 bytes.
291 btape: btape.c:857 Wrote block to device.
292 btape: btape.c:855 Wrote one record of 64412 bytes.
293 btape: btape.c:857 Wrote block to device.
294 btape: btape.c:855 Wrote one record of 64412 bytes.
295 btape: btape.c:857 Wrote block to device.
296 btape: btape.c:410 Wrote EOF to /dev/nst0
297 btape: btape.c:387 Rewound /dev/nst0
298 btape: btape.c:693 Now moving to end of media.
299 btape: btape.c:427 Moved to end of media
300 We should be in file 3. I am at file 3. This is correct!
301 Now the important part, I am going to attempt to append to the tape.
303 === End Append files test ===
307 If you do not successfully complete the above test, please resolve the
308 problem(s) before attempting to use {\bf Bacula}. Depending on your tape
309 drive, the test may recommend that you add certain records to your
310 configuration. We strongly recommend that you do so and then re-run the above
311 test to insure it works the first time.
313 Some of the suggestions it provides for resolving the problems may or may not
314 be useful. If at all possible avoid using fixed blocking. If the test suddenly
315 starts to print a long series of:
325 then almost certainly, you are running your drive in fixed block mode rather
326 than variable block mode. See below for more help of resolving fix
327 versus variable block problems.
329 It is also possible that you have your drive
330 set in SysV tape drive mode. The drive must use BSD tape conventions.
331 See the section above on setting your {\bf Archive device} correctly.
333 For FreeBSD users, please see the notes below for doing further testing of
336 \subsubsection*{Linux SCSI Tricks}
337 \index[general]{Tricks!Linux SCSI}
338 \index[general]{Linux SCSI Tricks}
339 \addcontentsline{toc}{subsubsection}{Linux SCSI Tricks}
341 You can find out what SCSI devices you have by doing:
349 For example, I get the following:
354 Host: scsi2 Channel: 00 Id: 01 Lun: 00
355 Vendor: HP Model: C5713A Rev: H107
356 Type: Sequential-Access ANSI SCSI revision: 02
357 Host: scsi2 Channel: 00 Id: 04 Lun: 00
358 Vendor: SONY Model: SDT-10000 Rev: 0110
359 Type: Sequential-Access ANSI SCSI revision: 02
363 The above represents first an autochanger and second a simple
364 tape drive. The HP changer (the first entry) uses the same SCSI channel
365 for data and for control, so in Bacula, you would use:
368 Archive Device = /dev/nst0
369 Changer Device = /dev/sg0
373 If you want to remove the SDT-10000 device, you can do so as root with:
377 echo "scsi remove-single-device 2 0 4 0">/proc/scsi/scsi
381 and you can put add it back with:
385 echo "scsi add-single-device 2 0 4 0">/proc/scsi/scsi
389 where the 2 0 4 0 are the Host, Channel, Id, and Lun as seen on the output
390 from {\bf cat /proc/scsi/scsi}. Note, the Channel must be specified as
393 Below is a slightly more complicated output, which is a single autochanger
394 with two drives, and which operates the changer on a different channel
395 from from the drives:
400 Host: scsi0 Channel: 00 Id: 00 Lun: 00
401 Vendor: ATA Model: WDC WD1600JD-75H Rev: 08.0
402 Type: Direct-Access ANSI SCSI revision: 05
403 Host: scsi2 Channel: 00 Id: 04 Lun: 00
404 Vendor: HP Model: Ultrium 2-SCSI Rev: F6CH
405 Type: Sequential-Access ANSI SCSI revision: 03
406 Host: scsi2 Channel: 00 Id: 05 Lun: 00
407 Vendor: HP Model: Ultrium 2-SCSI Rev: F6CH
408 Type: Sequential-Access ANSI SCSI revision: 03
409 Host: scsi2 Channel: 00 Id: 06 Lun: 00
410 Vendor: OVERLAND Model: LXB Rev: 0106
411 Type: Medium Changer ANSI SCSI revision: 02
415 The above tape drives are accessed on /dev/nst0 and /dev/nst1, while
416 the control channel for those two drives is /dev/sg3.
421 \subsection*{Tips for Resolving Problems}
422 \index[general]{Problems!Tips for Resolving}
423 \index[general]{Tips for Resolving Problems}
424 \addcontentsline{toc}{subsection}{Tips for Resolving Problems}
426 \label{CannotRestore}
427 \subsubsection*{Bacula Saves But Cannot Restore Files}
428 \index[general]{Files!Bacula Saves But Cannot Restore}
429 \index[general]{Bacula Saves But Cannot Restore Files}
430 \addcontentsline{toc}{subsubsection}{Bacula Saves But Cannot Restore Files}
432 If you are getting error messages such as:
436 Volume data error at 0:1! Wanted block-id: "BB02", got "". Buffer discarded
440 It is very likely that Bacula has tried to do block positioning and ended up
441 at an invalid block. This can happen if your tape drive is in fixed block mode
442 while Bacula's default is variable blocks. Note that in such cases, Bacula is
443 perfectly able to write to your Volumes (tapes), but cannot position to read
446 There are two possible solutions.
449 \item The first and best is to always ensure that your drive is in variable
450 block mode. Note, it can switch back to fixed block mode on a reboot or if
451 another program uses the drive. So on such systems you need to modify the
452 Bacula startup files to explicitly set:
456 mt -f /dev/nst0 defblksize 0
460 or whatever is appropriate on your system. Note, if you are running a Linux
461 system, and the above command does not work, it is most likely because you
462 have not loaded the appropriate {\bf mt} package, which is often called
463 {\bf mt\_st}, but may differ according to your distribution.
465 \item The second possibility, especially, if Bacula wrote while the drive was
466 in fixed block mode, is to turn off block positioning in Bacula. This is done
471 Block Positioning = no
475 to the Device resource. This is not the recommended procedure because it can
476 enormously slow down recovery of files, but it may help where all else
477 fails. This directive is available in version 1.35.5 or later (and not yet
481 If you are getting error messages such as:
484 Volume data error at 0:0!
485 Block checksum mismatch in block=0 len=32625 calc=345678 blk=123456
489 You are getting tape read errors, and this is most likely due to
490 one of the following things:
492 \item An old or bad tape.
493 \item A dirty drive that needs cleaning (particularly for DDS drives).
494 \item A loose SCSI cable.
495 \item Old firmware in your drive. Make sure you have the latest firmware
497 \item Computer memory errors.
498 \item Over-clocking your CPU.
499 \item A bad SCSI card.
504 \subsubsection*{Bacula Cannot Open the Device}
505 \index[general]{Device!Bacula Cannot Open the}
506 \index[general]{Bacula Cannot Open the Device}
507 \addcontentsline{toc}{subsubsection}{Bacula Cannot Open the Device}
509 If you get an error message such as:
513 dev open failed: dev.c:265 stored: unable to open
514 device /dev/nst0:> ERR=No such device or address
518 the first time you run a job, it is most likely due to the fact that you
519 specified the incorrect device name on your {\bf Archive Device}.
521 If Bacula works fine with your drive, then all off a sudden you get error
522 messages similar to the one shown above, it is quite possible that your driver
523 module is being removed because the kernel deems it idle. This is done via
524 {\bf crontab} with the use of {\bf rmmod -a}. To fix the problem, you can
525 remove this entry from {\bf crontab}, or you can manually {\bf modprob} your
526 driver module (or add it to the local startup script). Thanks to Alan Brown
528 \label{IncorrectFiles}
530 \subsubsection*{Incorrect File Number}
531 \index[general]{Number!Incorrect File}
532 \index[general]{Incorrect File Number}
533 \addcontentsline{toc}{subsubsection}{Incorrect File Number}
535 When Bacula moves to the end of the medium, it normally uses the {\bf
536 ioctl(MTEOM)} function. Then Bacula uses the {\bf ioctl(MTIOCGET)} function to
537 retrieve the current file position from the {\bf mt\_fileno} field. Some SCSI
538 tape drivers will use a fast means of seeking to the end of the medium and in
539 doing so, they will not know the current file position and hence return a {\bf
540 -1}. As a consequence, if you get {\bf "This is NOT correct!"} in the
541 positioning tests, this may be the cause. You must correct this condition in
542 order for Bacula to work.
544 There are two possible solutions to the above problem of incorrect file
548 \item Figure out how to configure your SCSI driver to keep track of the file
549 position during the MTEOM request. This is the preferred solution.
550 \item Modify the {\bf Device} resource of your {\bf bacula-sd.conf} file to
555 Hardware End of File = no
559 This will cause Bacula to use the MTFSF request to seek to the end of the
560 medium, and Bacula will keep track of the file number itself.
563 \label{IncorrectBlocks}
564 \subsubsection*{Incorrect Number of Blocks or Positioning Errors during btape
566 \index[general]{Testing!Incorrect Number of Blocks or Positioning Errors
568 \index[general]{Incorrect Number of Blocks or Positioning Errors during btape
570 \addcontentsline{toc}{subsubsection}{Incorrect Number of Blocks or Positioning
571 Errors during btape Testing}
573 {\bf Bacula's} preferred method of working with tape drives (sequential
574 devices) is to run in variable block mode, and this is what is set by default.
575 You should first ensure that your tape drive is set for variable block mode
578 If your tape drive is in fixed block mode and you have told Bacula to use
579 different fixed block sizes or variable block sizes (default), you will get
580 errors when Bacula attempts to forward space to the correct block (the kernel
581 driver's idea of tape blocks will not correspond to Bacula's).
583 All modern tape drives support variable tape blocks, but some older drives (in
584 particular the QIC drives) as well as the ATAPI ide-scsi driver run only in
585 fixed block mode. The Travan tape drives also apparently must run in fixed
586 block mode (to be confirmed).
588 Even in variable block mode, with the exception of the first record on the
589 second or subsequent volume of a multi-volume backup, Bacula will write blocks
590 of a fixed size. However, in reading a tape, Bacula will assume that for each
591 read request, exactly one block from the tape will be transferred. This the
592 most common way that tape drives work and is well supported by {\bf Bacula}.
594 Drives that run in fixed block mode can cause serious problems for Bacula if
595 the drive's block size does not correspond exactly to {\bf Bacula's} block
596 size. In fixed block size mode, drivers may transmit a partial block or
597 multiple blocks for a single read request. From {\bf Bacula's} point of view,
598 this destroys the concept of tape blocks. It is much better to run in variable
599 block mode, and almost all modern drives (the OnStream is an exception) run in
600 variable block mode. In order for Bacula to run in fixed block mode, you must
601 include the following records in the Storage daemon's Device resource
606 Minimum Block Size = nnn
607 Maximum Block Size = nnn
611 where {\bf nnn} must be the same for both records and must be identical to the
612 driver's fixed block size.
614 We recommend that you avoid this configuration if at all possible by using
615 variable block sizes.
617 If you must run with fixed size blocks, make sure they are not 512 bytes. This
618 is too small and the overhead that Bacula has with each record will become
619 excessive. If at all possible set any fixed block size to something like
620 64,512 bytes or possibly 32,768 if 64,512 is too large for your drive. See
621 below for the details on checking and setting the default drive block size.
623 To recover files from tapes written in fixed block mode, see below.
626 \subsubsection*{Ensuring that the Tape Modes Are Properly Set -- {\bf Linux
628 \index[general]{Ensuring that the Tape Modes Are Properly Set -- Linux Only}
629 \index[general]{Only!Ensuring that the Tape Modes Are Properly Set -- Linux}
630 \addcontentsline{toc}{subsubsection}{Ensuring that the Tape Modes Are Properly
633 If you have a modern SCSI tape drive and you are having problems with the {\bf
634 test} command as noted above, it may be that some program has set one or more
635 of your SCSI driver's options to non-default values. For example, if your
636 driver is set to work in SysV manner, Bacula will not work correctly because
637 it expects BSD behavior. To reset your tape drive to the default values, you
638 can try the following, but {\bf ONLY} if you have a SCSI tape drive on a {\bf
644 mt -f /dev/nst0 rewind
645 mt -f /dev/nst0 stoptions buffer-writes async-writes read-ahead
649 The above commands will clear all options and then set those specified. None
650 of the specified options are required by Bacula, but a number of other options
651 such as SysV behavior must not be set. Bacula does not support SysV tape
652 behavior. On systems other than Linux, you will need to consult your {\bf mt}
653 man pages or documentation to figure out how to do the same thing. This should
654 not really be necessary though -- for example, on both Linux and Solaris
655 systems, the default tape driver options are compatible with Bacula.
656 On Solaris systems, you must take care to specify the correct device
657 name on the {\bf Archive device} directive. See above for more details.
659 You may also want to ensure that no prior program has set the default block
660 size, as happened to one user, by explicitly turning it off with:
664 mt -f /dev/nst0 defblksize 0
668 If you are running a Linux
669 system, and the above command does not work, it is most likely because you
670 have not loaded the appropriate {\bf mt} package, which is often called
671 {\bf mt\_st}, but may differ according to your distribution.
673 If you would like to know what options you have set before making any of the
674 changes noted above, you can now view them on Linux systems, thanks to a tip
675 provided by Willem Riede. Do the following:
680 mt -f /dev/nst0 stsetoptions 0
681 grep st0 /var/log/messages
685 and you will get output that looks something like the following:
689 kernel: st0: Mode 0 options: buffer writes: 1, async writes: 1, read ahead: 1
690 kernel: st0: can bsr: 0, two FMs: 0, fast mteom: 0, auto lock: 0,
691 kernel: st0: defs for wr: 0, no block limits: 0, partitions: 0, s2 log: 0
692 kernel: st0: sysv: 0 nowait: 0
696 Note, I have chopped off the beginning of the line with the date and machine
697 name for presentation purposes.
699 Some people find that the above settings only last until the next reboot, so
700 please check this otherwise you may have unexpected problems.
702 Beginning with Bacula version 1.35.8, if Bacula detects that you are running
703 in variable block mode, it will attempt to set your drive appropriately. All
704 OSes permit setting variable block mode, but some OSes do not permit setting
705 the other modes that Bacula needs to function properly.
708 \subsubsection*{Checking and Setting Tape Hardware Compression and Blocking
710 \index[general]{Checking and Setting Tape Hardware Compression and Blocking
712 \index[general]{Size!Checking and Setting Tape Hardware Compression and
714 \addcontentsline{toc}{subsubsection}{Checking and Setting Tape Hardware
715 Compression and Blocking Size}
717 As far as I can tell, there is no way with the {\bf mt} program to check if
718 your tape hardware compression is turned on or off. You can, however, turn it
719 on by using (on Linux):
724 mt -f /dev/nst0 defcompression 1
728 and of course, if you use a zero instead of the one at the end, you will turn
731 If you have built the {\bf mtx} program in the {\bf depkgs} package, you can
732 use tapeinfo to get quite a bit of information about your tape drive even if
733 it is not an autochanger. This program is called using the SCSI control
734 device. On Linux for tape drive /dev/nst0, this is usually /dev/sg0, while on
735 FreeBSD for /dev/nsa0, the control device is often /dev/pass2. For example on
736 my DDS-4 drive (/dev/nst0), I get the following:
741 Product Type: Tape Drive
743 Product ID: 'C5713A '
752 Medium Type: Not Loaded
758 where the {\bf DataCompEnabled: yes} means that tape hardware compression is
759 turned on. You can turn it on and off (yes|no) by using the {\bf mt}
760 commands given above. Also, this output will tell you if the {\bf BlockSize}
761 is non-zero and hence set for a particular block size. Bacula is not likely to
762 work in such a situation because it will normally attempt to write blocks of
763 64,512 bytes, except the last block of the job which will generally be
764 shorter. The first thing to try is setting the default block size to zero
765 using the {\bf mt -f /dev/nst0 defblksize 0} command as shown above.
766 On FreeBSD, this would be something like: {\bf mt -f /dev/nsa0 blocksize 0}.
768 On some operating systems with some tape drives, the amount of data that
769 can be written to the tape and whether or not compression is enabled is
770 determined by the density usually the {\bf mt -f /dev/nst0 setdensity xxx} command.
771 Often {\bf mt -f /dev/nst0 status} will print out the current
772 density code that is used with the drive. Most systems, but unfortunately
773 not all, set the density to the maximum by default. On some systems, you
774 can also get a list of all available density codes with:
775 {\bf mt -f /dev/nst0 densities} or a similar {\bf mt} command.
776 Note, for DLT and SDLT devices, no-compression versus compression is very
777 often controlled by the density code. On FreeBSD systems, the compression
778 mode is set using {\bf mt -f /dev/nsa0 comp xxx} where xxx is the
779 mode you want. In general, see {\bf man mt} for the options available on
782 Note, some of the above {\bf mt} commands may not be persistent depending
783 on your system configuration. That is they may be reset if a program
784 other than Bacula uses the drive or, as is frequently the case, on reboot
787 If your tape drive requires fixed block sizes (very unusual), you can use the
792 Minimum Block Size = nnn
793 Maximum Block Size = nnn
797 in your Storage daemon's Device resource to force Bacula to write fixed size
798 blocks (where you sent nnn to be the same for both of the above records). This
799 should be done only if your drive does not support variable block sizes, or
800 you have some other strong reasons for using fixed block sizes. As mentioned
801 above, a small fixed block size of 512 or 1024 bytes will be very inefficient.
802 Try to set any fixed block size to something like 64,512 bytes or larger if
803 your drive will support it.
805 Also, note that the {\bf Medium Type} field of the output of {\bf tapeinfo}
806 reports {\bf Not Loaded}, which is not correct. As a consequence, you should
807 ignore that field as well as the {\bf Attached Changer} field.
809 To recover files from tapes written in fixed block mode, see below.
812 \subsubsection*{Tape Modes on FreeBSD}
813 \index[general]{FreeBSD!Tape Modes on}
814 \index[general]{Tape Modes on FreeBSD}
815 \addcontentsline{toc}{subsubsection}{Tape Modes on FreeBSD}
817 On most FreeBSD systems such as 4.9 and most tape drives, Bacula should run
822 mt -f /dev/nsa0 seteotmodel 2
823 mt -f /dev/nsa0 blocksize 0
824 mt -f /dev/nsa0 comp enable
828 You might want to put those commands in a startup script to make sure your
829 tape driver is properly initialized before running Bacula, because
830 depending on your system configuration, these modes may be reset if a
831 program other than Bacula uses the drive or when your system is rebooted.
833 Then according to what the {\bf btape test} command returns, you will probably
834 need to set the following (see below for an alternative):
838 Hardware End of Medium = no
840 Backward Space Record = no
841 Backward Space File = no
842 Fast Forward Space File = no
847 Then be sure to run some append tests with Bacula where you start and stop
848 Bacula between appending to the tape, or use {\bf btape} version 1.35.1 or
849 greater, which includes simulation of stopping/restarting Bacula.
851 Please see the file {\bf platforms/freebsd/pthreads-fix.txt} in the main
852 Bacula directory concerning {\bf important} information concerning
853 compatibility of Bacula and your system. A much more optimal Device
854 configuration is shown below, but does not work with all tape drives. Please
855 test carefully before putting either into production.
857 Note, for FreeBSD 4.10-RELEASE, using a Sony TSL11000 L100 DDS4 with an
858 autochanger set to variable block size and DCLZ compression, Brian McDonald
859 reports that to get Bacula to append correctly between Bacula executions,
860 the correct values to use are:
864 mt -f /dev/nsa0 seteotmodel 1
865 mt -f /dev/nsa0 blocksize 0
866 mt -f /dev/nsa0 comp enable
874 Hardware End of Medium = no
876 Backward Space Record = no
877 Backward Space File = no
878 Fast Forward Space File = yes
883 This has been confirmed by several other people using different hardware. This
884 configuration is the preferred one because it uses one EOF and no backspacing
885 at the end of the tape, which works much more efficiently and reliably with
888 Finally, here is a Device configuration that Danny Butroyd reports to work
889 correctly with the Overland Powerloader tape library using LT0-2 and
894 # Overland Powerloader LT02 - 17 slots single drive
898 Archive Device = /dev/nsa0
899 AutomaticMount = yes;
901 RemovableMedia = yes;
903 Changer Command = "/usr/local/sbin/mtx-changer %c %o %S %a %d"
904 Changer Device = /dev/pass2
906 Alert Command = "sh -c 'tapeinfo -f %c |grep TapeAlert|cat'"
908 # FreeBSD Specific Settings
909 Offline On Unmount = no
910 Hardware End of Medium = no
912 Backward Space Record = no
913 Fast Forward Space File = no
917 The following Device resource works fine with Dell PowerVault 110T and
918 120T devices on both FreeBSD 5.3 and on NetBSD 3.0. It also works
919 with Sony AIT-2 drives on FreeBSD.
924 # FreeBSD/NetBSD Specific Settings
925 Hardware End of Medium = no
927 Backward Space Record = no
928 Fast Forward Space File = yes
934 On FreeBSD version 6.0, it is reported that you can even set
935 Backward Space Record = yes.
939 \subsubsection*{Finding your Tape Drives and Autochangers on FreeBSD}
940 \index[general]{FreeBSD!Finding your Tape Drives and Autochangers}
941 \index[general]{Finding your Tape Drives and Autochangers on FreeBSD}
942 \addcontentsline{toc}{subsubsection}{Finding your Tape Drives and
943 Autochangers on FreeBSD}
945 On FreeBSD, you can do a {\bf camcontrol devlist} as root to determine what
946 drives and autochangers you have. For example,
950 undef# camcontrol devlist
951 at scbus0 target 2 lun 0 (pass0,sa0)
952 at scbus0 target 4 lun 0 (pass1,sa1)
953 at scbus0 target 4 lun 1 (pass2)
957 from the above, you can determine that there is a tape drive on {\bf /dev/sa0}
958 and another on {\bf /dev/sa1} in addition since there is a second line for the
959 drive on {\bf /dev/sa1}, you know can assume that it is the control device for
960 the autochanger (i.e. {\bf /dev/pass2}). It is also the control device name to
961 use when invoking the tapeinfo program. E.g.
965 tapeinfo -f /dev/pass2
971 \subsubsection*{Using the OnStream driver on Linux Systems}
972 \index[general]{Using the OnStream driver on Linux Systems}
973 \index[general]{Systems!Using the OnStream driver on Linux}
974 \addcontentsline{toc}{subsubsection}{Using the OnStream driver on Linux
977 Bacula version 1.33 (not 1.32x) is now working and ready for testing with the
978 OnStream kernel osst driver version 0.9.14 or above. Osst is available from:
979 \elink{http://sourceforge.net/projects/osst/}
980 {http://sourceforge.net/projects/osst/}.
982 To make Bacula work you must first load the new driver then, as root, do:
986 mt -f /dev/nosst0 defblksize 32768
990 Also you must add the following to your Device resource in your Storage
995 Minimum Block Size = 32768
996 Maximum Block Size = 32768
1000 Here is a Device specification provided by Michel Meyers that is known to
1006 Name = "Onstream DI-30"
1007 Media Type = "ADR-30"
1008 Archive Device = /dev/nosst0
1009 Minimum Block Size = 32768
1010 Maximum Block Size = 32768
1011 Hardware End of Medium = yes
1013 Backward Space File = yes
1014 Fast Forward Space File = yes
1016 AutomaticMount = yes
1018 Removable Media = yes
1023 \subsection*{Hardware Compression on EXB-8900}
1024 \index[general]{Hardware Compression on EXB-8900}
1025 \index[general]{EXB-8900!Hardware Compression}
1026 \addcontentsline{to}{subsection}{Hardware Compression on EXB-8900}
1027 To active, check, or disable the hardware compression feature
1028 on an EXB-8900, use the exabyte MammothTool. You can get it here:
1029 \elink{http://www.exabyte.com/support/online/downloads/index.cfm}
1030 {http://www.exabyte.com/support/online/downloads/index.cfm}.
1031 There is a Solaris version of this tool. With option -C 0 or 1 you
1032 can disable or activate compression. Start this tool without any
1033 options for a small reference.
1036 \subsubsection*{Using btape to Simulate Filling a Tape}
1037 \index[general]{Using btape to Simulate Filling a Tape}
1038 \index[general]{Tape!Using btape to Simulate Filling a}
1039 \addcontentsline{toc}{subsubsection}{Using btape to Simulate Filling a
1042 Because there are often problems with certain tape drives or systems when end
1043 of tape conditions occur, {\bf btape} has a special command {\bf fill} that
1044 causes it to write random data to a tape until the tape fills. It then writes
1045 at least one more Bacula block to a second tape. Finally, it reads back both
1046 tapes to ensure that the data has been written in a way that Bacula can
1047 recover it. Note, there is also a single tape option as noted below, which you
1048 should use rather than the two tape test. See below for more details.
1050 This can be an extremely time consuming process (here it is about 6 hours) to
1051 fill a full tape. Note, that btape writes random data to the tape when it is
1052 filling it. This has two consequences: 1. it takes a bit longer to generate
1053 the data, especially on slow CPUs. 2. the total amount of data is
1054 approximately the real physical capacity of your tape, regardless of whether
1055 or not the tape drive compression is on or off. This is because random data
1056 does not compress very much.
1058 To begin this test, you enter the {\bf fill} command and follow the
1059 instructions. There are two options: the simple single tape option and the
1060 multiple tape option. Please use only the simple single tape option because
1061 the multiple tape option still doesn't work totally correctly. If the single
1062 tape option does not succeed, you should correct the problem before using
1064 \label{RecoveringFiles}
1066 \subsection*{Recovering Files Written to Tape With Fixed Block Sizes}
1067 \index[general]{Recovering Files Written to Tape With Fixed Block Sizes}
1068 \index[general]{Sizes!Recovering Files Written to Tape With Fixed Block}
1069 \addcontentsline{toc}{subsection}{Recovering Files Written to Tape With Fixed
1072 If you have been previously running your tape drive in fixed block mode
1073 (default 512) and Bacula with variable blocks (default), then in version
1074 1.32f-x and 1.34 and above, Bacula will fail to recover files because it does
1075 block spacing, and because the block sizes don't agree between your tape drive
1076 and Bacula it will not work.
1078 The long term solution is to run your drive in variable block mode as
1079 described above. However, if you have written tapes using fixed block sizes,
1080 this can be a bit of a pain. The solution to the problem is: while you are
1081 doing a restore command using a tape written in fixed block size, ensure that
1082 your drive is set to the fixed block size used while the tape was written.
1083 Then when doing the {\bf restore} command in the Console program, do not
1084 answer the prompt {\bf yes/mod/no}. Instead, edit the bootstrap file (the
1085 location is listed in the prompt) using any ASCII editor. Remove all {\bf
1086 VolBlock} lines in the file. When the file is re-written, answer the question,
1087 and Bacula will run without using block positioning, and it should recover
1091 \subsection*{Tape Blocking Modes}
1092 \index[general]{Modes!Tape Blocking}
1093 \index[general]{Tape Blocking Modes}
1094 \addcontentsline{toc}{subsection}{Tape Blocking Modes}
1096 SCSI tapes may either be written in {\bf variable} or {\bf fixed} block sizes.
1097 Newer drives support both modes, but some drives such as the QIC devices
1098 always use fixed block sizes. Bacula attempts to fill and write complete
1099 blocks (default 65K), so that in normal mode (variable block size), Bacula
1100 will always write blocks of the same size except the last block of a Job. If
1101 Bacula is configured to write fixed block sizes, it will pad the last block of
1102 the Job to the correct size. Bacula expects variable tape block size drives to
1103 behave as follows: Each write to the drive results in a single record being
1104 written to the tape. Each read returns a single record. If you request less
1105 bytes than are in the record, only those number of bytes will be returned, but
1106 the entire logical record will have been read (the next read will retrieve the
1107 next record). Thus data from a single write is always returned in a single
1108 read, and sequentially written records are returned by sequential reads.
1110 Bacula expects fixed block size tape drives to behave as follows: If a write
1111 length is greater than the physical block size of the drive, the write will be
1112 written as two blocks each of the fixed physical size. This single write may
1113 become multiple physical records on the tape. (This is not a good situation).
1114 According to the documentation, one may never write an amount of data that is
1115 not the exact multiple of the blocksize (it is not specified if an error
1116 occurs or if the the last record is padded). When reading, it is my
1117 understanding that each read request reads one physical record from the tape.
1118 Due to the complications of fixed block size tape drives, you should avoid
1119 them if possible with Bacula, or you must be ABSOLUTELY certain that you use
1120 fixed block sizes within Bacula that correspond to the physical block size of
1121 the tape drive. This will ensure that Bacula has a one to one correspondence
1122 between what it writes and the physical record on the tape.
1124 Please note that Bacula will not function correctly if it writes a block and
1125 that block is split into two or more physical records on the tape. Bacula
1126 assumes that each write causes a single record to be written, and that it can
1127 sequentially recover each of the blocks it has written by using the same
1128 number of sequential reads as it had written.
1130 \subsection*{Details of Tape Modes}
1131 \index[general]{Modes!Details}
1132 \index[general]{Details of Tape Modes}
1133 \addcontentsline{toc}{subsection}{Details of Tape Modes}
1134 Rudolf Cejka has provided the following information concerning
1135 certain tape modes and MTEOM.
1139 It is always possible to position filemarks or blocks, whereas
1140 positioning to the end-of-data is only optional feature, however it is
1141 implemented very often. SCSI specification also talks about optional
1142 sequential filemarks, setmarks and sequential setmarks, but these are not
1143 implemented so often. Modern tape drives keep track of file positions in
1144 built-in chip (AIT, LTO) or at the beginning of the tape (SDLT), so there
1145 is not any speed difference, if end-of-data or filemarks is used (I have
1146 heard, that LTO-1 from all 3 manufacturers do not use its chip for file
1147 locations, but a tape as in SDLT case, and I'm not sure about LTO-2 and
1148 LTO-3 case). However there is a big difference, that end-of-data ignores
1149 file position, whereas filemarks returns the real number of skipped
1150 files, so OS can track current file number just in filemarks case.
1153 Solaris does use just SCSI SPACE Filemarks, it does not support SCSI
1154 SPACE End-of-data. When MTEOM is called, Solaris does use SCSI SPACE
1155 Filemarks with count = 1048576 for fast mode, and combination of SCSI
1156 SPACE Filemarks with count = 1 with SCSI SPACE Blocks with count = 1 for
1157 slow mode, so EOD mark on the tape on some older tape drives is not
1158 skipped. File number is always tracked for MTEOM.
1160 Linux does support both SCSI SPACE Filemarks and End-of-data: When MTEOM
1161 is called in MT\_ST\_FAST\_MTEOM mode, SCSI SPACE End-of-data is used.
1162 In the other case, SCSI SPACE Filemarks with count =
1164 There is no real slow mode like in Solaris - I just expect, that for
1165 older tape drives Filemarks may be slower than End-of-data, but not so
1166 much as in Solaris slow mode. File number is tracked for MTEOM just
1167 without MT\_ST\_FAST\_MTEOM - when MT\_ST\_FAST\_MTEOM is used, it is not.
1169 FreeBSD does support both SCSI SPACE Filemarks and End-of-data, but when
1170 MTEOD (MTEOM) is called, SCSI SPACE End-of-data is always used. FreeBSD
1171 never use SCSI SPACE Filemarks for MTEOD. File number is never tracked
1175 When {\bf Hardware End of Medium = Yes} is used, MTEOM is called, but it
1176 does not mean, that hardware End-of-data must be used. When Hardware End
1177 of Medium = No, if Fast Forward Space File = Yes, MTFSF with count =
1178 32767 is used, else Block Read with count = 1 with Forward Space File
1179 with count = 1 is used, which is really very slow.
1181 \item [Hardware End of Medium = Yes|No]
1182 The name of this option is misleading and is the source of confusion,
1183 because it is not the hardware EOM, what is really switched here.
1185 If I use Yes, OS must not use SCSI SPACE End-of-data, because Bacula
1186 expects, that there is tracked file number, which is not supported by
1187 SCSI specification. Instead, the OS have to use SCSI SPACE Filemarks.
1189 If I use No, an action depends on Fast Forward Space File.
1191 When I set {\bf Hardware End of Medium = no}
1192 and {\bf Fast Forward Space File = no}
1193 file positioning was very slow
1194 on my LTO-3 (about ten to 100 minutes), but
1196 with {\bf Hardware End of Medium = no} and
1197 {\bf Fast Forward Space File = yes}, the time is ten to
1198 100 times faster (about one to two minutes).
1202 \subsection*{Autochanger Errors}
1203 \index[general]{Errors!Autochanger}
1204 \index[general]{Autochanger Errors}
1205 \addcontentsline{toc}{subsection}{Autochanger Errors}
1207 If you are getting errors such as:
1211 3992 Bad autochanger "load slot 1, drive 1": ERR=Child exited with code 1.
1215 and you are running your Storage daemon as non-root, then most likely
1216 you are having permissions problems with the control channel. Running
1217 as root, set permissions on /dev/sgX so that the userid and group of
1218 your Storage daemon can access the device. You need to ensure that you
1219 all access to the proper control device, and if you don't have any
1220 SCSI disk drives (including SATA drives), you might want to change
1221 the permissions on /dev/sg*.
1223 \subsection*{Syslog Errors}
1224 \index[general]{Errors!Syslog}
1225 \index[general]{Syslog Errors}
1226 \addcontentsline{toc}{subsection}{Syslog Errors}
1228 If you are getting errors such as:
1232 : kernel: st0: MTSETDRVBUFFER only allowed for root
1236 you are most likely running your Storage daemon as non-root, and
1237 Bacula is attempting to set the correct OS buffering to correspond
1238 to your Device resource. Most OSes allow only root to issue this
1239 ioctl command. In general, the message can be ignored providing
1240 you are sure that your OS parameters are properly configured as
1241 described earlier in this manual. If you are running your Storage daemon
1242 as root, you should not be getting these system log messages, and if
1243 you are, something is probably wrong.