4 \section*{Automated Disk Backup}
5 \label{_ChapterStart11}
6 \index[general]{Volumes!Using Pools to Manage }
7 \index[general]{Disk!Automated Backup}
8 \index[general]{Using Pools to Manage Volumes }
9 \index[general]{Automated Disk Backup}
10 \addcontentsline{toc}{section}{Using Pools to Manage Volumes}
11 \addcontentsline{toc}{section}{Automated Disk Backup}
13 If you manage 5 or 10 machines and have a nice tape backup, you don't need
14 Pools, and you may wonder what they are good for. In this chapter, you will
15 see that Pools can help you optimize disk storage space. The same techniques
16 can be applied to a shop that has multiple tape drives, or that wants to mount
17 various different Volumes to meet their needs.
19 The rest of this chapter will give an example involving backup to disk
20 Volumes, but most of the information applies equally well to tape Volumes.
23 \subsection*{The Problem}
24 \index[general]{Problem }
25 \addcontentsline{toc}{subsection}{Problem}
27 A site that I administer (a charitable organization) had a tape DDS-3 tape
28 drive that was failing. The exact reason for the failure is still unknown.
29 Worse yet, their full backup size is about 15GB whereas the capacity of their
30 broken DDS-3 was at best 8GB (rated 6/12). A new DDS-4 tape drive and the
31 necessary cassettes was more expensive than their budget could handle.
34 \subsection*{The Solution}
35 \index[general]{Solution }
36 \addcontentsline{toc}{subsection}{Solution}
38 They want to maintain 6 months of backup data, and be able to access the old
39 files on a daily basis for a week, a weekly basis for a month, then monthly
40 for 6 months. In addition, offsite capability was not needed (well perhaps
41 it really is, but it was never used). Their daily changes amount to about
42 300MB on the average, or about 2GB per week.
44 As a consequence, the total volume of data they need to keep to meet their
45 needs is about 100GB (15GB x 6 + 2GB x 5 + 0.3 x 7) = 102.1GB.
47 The chosen solution was to buy a 120GB hard disk for next to nothing -- far
48 less than 1/10th the price of a tape drive and the cassettes to handle the
49 same amount of data, and to have Bacula write to disk files.
51 The rest of this chapter will explain how to setup Bacula so that it would
52 automatically manage a set of disk files with the minimum intervention on my
53 part. The system has been running since 22 January 2004 until today (08 April
54 2004) with no intervention. Since we have not yet crossed the six month
55 boundary, we still lack some data to be sure the system performs as desired.
58 \subsection*{Overall Design}
59 \index[general]{Overall Design }
60 \index[general]{Design!Overall }
61 \addcontentsline{toc}{subsection}{Overall Design}
63 Getting Bacula to write to disk rather than tape in the simplest case is
64 rather easy, and is documented in the previous chapter. In addition, all the
65 directives discussed here are explained in that chapter. We'll leave it to you
66 to look at the details there. If you haven't read it and are not familiar with
67 Pools, you probably should at least read it once quickly for the ideas before
70 One needs to consider about what happens if we have only a single large Bacula
71 Volume defined on our hard disk. Everything works fine until the Volume fills,
72 then Bacula will ask you to mount a new Volume. This same problem applies to
73 the use of tape Volumes if your tape fills. Being a hard disk and the only one
74 you have, this will be a bit of a problem. It should be obvious that it is
75 better to use a number of smaller Volumes and arrange for Bacula to
76 automatically recycle them so that the disk storage space can be reused. The
77 other problem with a single Volume, is that at the current time (1.34.0)
78 Bacula does not seek within a disk Volume, so restoring a single file can take
79 more time than one would expect.
81 As mentioned, the solution is to have multiple Volumes, or files on the disk.
82 To do so, we need to limit the use and thus the size of a single Volume, by
83 time, by number of jobs, or by size. Any of these would work, but we chose to
84 limit the use of a single Volume by putting a single job in each Volume with
85 the exception of Volumes containing Incremental backup where there will be 6
86 jobs (a week's worth of data) per volume. The details of this will be
89 The next problem to resolve is recycling of Volumes. As you noted from above,
90 the requirements are to be able to restore monthly for 6 months, weekly for a
91 month, and daily for a week. So to simplify things, why not do a Full save
92 once a month, a Differential save once a week, and Incremental saves daily.
93 Now since each of these different kinds of saves needs to remain valid for
94 differing periods, the simplest way to do this (and possibly the only) is to
95 have a separate Pool for each backup type.
97 The decision was to use three Pools: one for Full saves, one for Differential
98 saves, and one for Incremental saves, and each would have a different number
99 of volumes and a different Retention period to accomplish the requirements.
102 \subsubsection*{Full Pool}
103 \index[general]{Pool!Full }
104 \index[general]{Full Pool }
105 \addcontentsline{toc}{subsubsection}{Full Pool}
107 Putting a single Full backup on each Volume, will require six Full save
108 Volumes, and a retention period of six months. The Pool needed to do that is:
117 Volume Retention = 6 months
118 Maximum Volume Jobs = 1
125 Since these are disk Volumes, no space is lost by having separate Volumes for
126 each backup (done once a month in this case). The items to note are the
127 retention period of six months (i.e. they are recycled after 6 months), that
128 there is one job per volume (Maximum Volume Jobs = 1), the volumes will be
129 labeled Full-0001, ... Full-0006 automatically. One could have labeled these
130 manual from the start, but why not use the features of Bacula.
133 \subsubsection*{Differential Pool}
134 \index[general]{Pool!Differential }
135 \index[general]{Differential Pool }
136 \addcontentsline{toc}{subsubsection}{Differential Pool}
138 For the Differential backup Pool, we choose a retention period of a bit longer
139 than a month and ensure that there is at least one Volume for each of the
140 maximum of five weeks in a month. So the following works:
149 Volume Retention = 40 days
150 Maximum Volume Jobs = 1
157 As you can see, the Differential Pool can grow to a maximum of six volumes,
158 and the Volumes are retained 40 days and thereafter they can be recycled. Finally
159 there is one job per volume. This, of course, could be tightened up a lot, but
160 the expense here is a few GB which is not too serious.
163 \subsubsection*{Incremental Pool}
164 \index[general]{Incremental Pool }
165 \index[general]{Pool!Incremental }
166 \addcontentsline{toc}{subsubsection}{Incremental Pool}
168 Finally, here is the resource for the Incremental Pool:
177 Volume Retention = 20 days
178 Maximum Volume Jobs = 6
185 We keep the data for 20 days rather than just a week as the needs require. To
186 reduce the proliferation of volume names, we keep a week's worth of data (6
187 incremental backups) in each Volume. In practice, the retention period should
188 be set to just a bit more than a week and keep only two or three volumes
189 instead of five. Again, the lost is very little and as the system reaches the
190 full steady state, we can adjust these values so that the total disk usage
191 doesn't exceed the disk capacity.
194 \subsection*{The Actual Conf Files}
195 \index[general]{Files!Actual Conf }
196 \index[general]{Actual Conf Files }
197 \addcontentsline{toc}{subsection}{Actual Conf Files}
199 The following example shows you the actual files used, with only a few minor
200 modifications to simplify things.
202 The Director's configuration file is as follows:
206 Director { # define myself
209 QueryFile = "/home/bacula/bin/query.sql"
210 WorkingDirectory = "/home/bacula/working"
211 PidDirectory = "/home/bacula/working"
212 Maximum Concurrent Jobs = 1
216 # By default, this job will back up to disk in /tmp
222 Schedule = "WeeklyCycle"
226 Full Backup Pool = Full-Pool
227 Incremental Backup Pool = Inc-Pool
228 Differential Backup Pool = Diff-Pool
229 Write Bootstrap = "/home/bacula/working/client.bsr"
232 # List of files to be backed up
235 Include = signature=SHA1 compression=GZIP9 {
241 /proc /tmp /.journal /.fsck
246 Run = Full 1st sun at 1:05
247 Run = Differential 2nd-5th sun at 1:05
248 Run = Incremental mon-sat at 1:05
256 AutoPrune = yes # Prune expired Jobs/Files
257 Job Retention = 6 months
258 File Retention = 60 days
270 dbname = bacula; user = bacula; password = ""
275 Recycle = yes # automatically recycle Volumes
276 AutoPrune = yes # Prune expired volumes
277 Volume Retention = 6 months
278 Maximum Volume Jobs = 1
285 Recycle = yes # automatically recycle Volumes
286 AutoPrune = yes # Prune expired volumes
287 Volume Retention = 20 days
288 Maximum Volume Jobs = 6
297 Volume Retention = 40 days
298 Maximum Volume Jobs = 1
304 mailcommand = "bsmtp -h mail.domain.com -f \"\(Bacula\) %r\"
305 -s \"Bacula: %t %e of %c %l\" %r"
306 operatorcommand = "bsmtp -h mail.domain.com -f \"\(Bacula\) %r\"
307 -s \"Bacula: Intervention needed for %j\" %r"
308 mail = root@domain.com = all, !skipped
309 operator = root@domain.com = mount
310 console = all, !skipped, !saved
311 append = "/home/bacula/bin/log" = all, !skipped
316 and the Storage daemon's configuration file is:
320 Storage { # definition of myself
322 SDPort = 9103 # Director's port
323 WorkingDirectory = "/home/bacula/working"
324 Pid Directory = "/home/bacula/working"
333 Archive Device = /files/bacula
334 LabelMedia = yes; # lets Bacula label unlabeled media
336 AutomaticMount = yes; # when device opened, read it
342 director = bacula-dir = all