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         Chapter 3. Excluding
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Chapter 3. Excluding


Andrew Hall

Original text

Stefan G. Weichinger

XML-conversion;Updates
AMANDA Core Team
<sgw@amanda.org>
Table of Contents


  Introduction

  Please_Read

  Before_We_Begin

  Choosing_an_exclude_mechanism


        Exclude_Mechanisms


  Expression

  Wildcard_Expansion

  Troubleshooting


        Broken_gnutar?

        The_ps_command_is_your_friend.



 Introduction

There are times when data needs to be excluded from a backup. When these times
arise be confident that Amanda has this capability. (Actually it's not Amanda,
it's tar.) There are three ways of excluding data in an Amanda backup:

* Exclude an individual item explicitly in the dumptype
* Utilize an "Exclude List"
* Do not include the data in the disklist

This document is based on Amanda 2.4.2 and some of this might not work with
older versions. This was compiled from my personal experience and with help
from the members of the amanda-users mailing list (mailto://amanda-
users@amanda.org) when I was originally setting this up, to whom I wish to
thank for all of their support.

 Please Read

As far as I am able to tell the only way to exclude files or directories with
Amanda is to use GNU-tar as the dump program (others?). The file system dump
programs provided with unix systems (e.g. dump, ufsdump) get data at a raw
drive level and generally do not allow exclusion of specific files or
directories.
The GNU version of tar, (GNU-tar or gtar), reads its data at a file system, (or
higher), level and does include the option to exclude specific files and/or
directories. It should be mentioned here that tar will change the access times
on files. Tar has the ability to preserve the access times however, doing so
effectively disables incremental backups since resetting the access time alters
the inode change time, which in turn causes the file to look like it needs to
be archived again.
The only exception that I am aware of is to just not include the data in
question in the disklist. This option may not be suitable for everyone's needs
and can confuse the issue some, so I have elected to include this mechanism in
its own section named Do_not_include_the_data_in_the_disklist.
For the purpose of this document an Amanda backup configuration named "exclude-
test" will be used. The machine that contains the tape drive which receives
data to be archived will be referred to as "SERVER". The machine that data is
being archived from will be referred to as "CLIENT". These two systems are
usually different machines but are not required to be, and may be the same
machine. Parts of this setup are on the server and some are on the client.

Note

When Amanda attempts to exclude a file or directory it does so relative to the
area being archived. For example if /var is in your disklist and you want to
exclude /var/log/somefile, then your exclude file would contain ./log/somefile.
You may use one exclude file in multiple dumptypes without any restriction.

 Before We Begin

The first step that should be taken is to verify that backups are currently
working. Connect to SERVER and run amcheck as your Amanda user, to verify that
there are no errors in the current setup.

  $ amcheck -cl CLIENT

Output should look something like below for success:

        Amanda Tape Server Host Check
        -----------------------------

        /path/to/holding-disk: 4771300 KB disk space available, that's plenty.
        Amanda Backup Client Hosts Check
        --------------------------------
        Client check: 1 host checked in 0.084 seconds, 0 problems found.

Next make sure that GNU-tar is the dump program currently in use. The easiest
way to tell if your dumptype is using gnutar is to run the following:

  $ amadmin exclude-test disklist CLIENT

Among all the output is the "program" value currently in use. This value is
also specified with the "program" option in the dumptype. If the dumptype has
the line "program GNUTAR" your setup should be ready to exclude data.
If GNU-tar is not in use add the line "program GNUTAR" to the dumptype, and
then run amcheck again to verify that backups should work. The capitalization
of GNUTAR is required.
The dumptype should look something like:

  define dumptype exclude-test {
  comment "test dumptype for documentation"
  priority high
  program "GNUTAR"
  }


 Choosing an exclude mechanism

If the need is to exclude only one file or directory then the easiest way to
accomplish this is to exclude an individual item explicitly in the dumptype. If
the need is to exclude multiple files or directories then use an Exclude List.

 Exclude Mechanisms


 Exclude an individual item explicitly in the dumptype

The easiest way to exclude a file or directory is to specify it with the
"exclude" option in the dumptype. This option accepts an argument of the file
or directory to be excluded. Amanda allows only one exclude option in any
dumptype at a time.

Note

UPDATE: Recent Amanda-releases bring the option "exclude append" which enables
the administrator to define more than one exclusion-pattern within one dumptype
without using a exclude-list. Please look at the amanda.conf.5-manpage for
details.
Any path specified to be excluded must be encapsulated with quotes. Continuing
with our example from above /var/log/somefile and using the same dumptype as
above, the dumptype would now look like:

  define dumptype exclude-test {
  comment "test dumptype for documentation"
  priority high
  program "GNUTAR"
  exclude "./log/somefile"
  }

Next run amcheck again to verify that there are no problems with the revised
Amanda configuration. If the data is not being excluded as expected please see
the Troubleshooting section below. This completes the setup of excluding an
individual item in the dumptype.

 Utilize an Exclude List

An exclude list is a file that resides on the CLIENT machine and contains paths
to be excluded, one per line. This file can be in any location on the CLIENT so
long as the same path is specified in the dumptype. Some find /usr/local/etc/
amanda an appropriate location, but it is up to you. I personally like to have
a subdirectory for exclude files but it is up to you where you place this file.
The exclude file may also be placed in the area being archived. This is an easy
way to have a different exclusion file for each disklist entry without needing
separate dumptype definitions. To use this technique, enter a path relative to
the area being archived as the exclude file below instead of an absolute path.
Connect to CLIENT and create the exclude directory as root. For example:

  $ mkdir -p /usr/local/etc/amanda/exclude
  $ cd /usr/local/etc/amanda/exclude

Next create the exclude list for Amanda to use. You can name the exclude file
anything you wish it to be. Create a file, and in this file place all paths to
files and directories that are to be excluded. Keeping with the /var example,
assume that /var/log/XFree86.0.log, and /var/log/maillog need to be excluded.
Remember that all paths are relative. The exclude list would look like:

  ./log/XFree86.0.log
  ./log/maillog

Make sure that permissions are restricted on this file. Run the following as
root, where exclude-filename is the name of the file you just created. For
example:

  $ chmod 644 /usr/local/etc/amanda/exclude/exclude-filename

This concludes the necessary configuration on the client.
Connect to SERVER and cd to the exclude-test Amanda configuration directory.
Edit the Amanda configuration file e.g. amanda.conf. Add an entry similar to
the following line, to the dumptype for the client in question, where the
exclude-filename is the file that was created on CLIENT in the step above
including the quotes. For example:

  exclude list "/usr/local/etc/amanda/exclude/exclude-filename"

The new dumptype should look something like:

  define dumptype exclude-test{
  comment "test dumptype for documentation"
  priority high
  program "GNUTAR"
  exclude list "/usr/local/etc/amanda/exclude/exclude-filename"
  }

Save the file. Run amcheck again to verify that there are no problems with the
revised Amanda configuration. If amcheck succeeds then run amdump to verify the
data is being excluded correctly. If the data is not being excluded as expected
please see the Troubleshooting section below. This completes the setup of an
exclude list.

 Do not include the data in the disklist

Amanda uses disklist entries to define which directories or partitions should
be archived. This allows us to exclude data by just not placing the data in
question in the disklist. Assume that there is a disk mounted on /example. The
directory /example has five subdirectories "a", "b", "c", "d", and "e". The
directories "a", "b", and "c" need to be archived, while "d" and "e" should
not. This can be accomplished by not specifying "d" and "e" in the disklist.
Using the same dumptype and host in the above examples the disklist would
contain:

  CLIENT /examples/a    exclude-test
  CLIENT /examples/b    exclude-test
  CLIENT /examples/c    exclude-test

Run amcheck to verify that Amanda is working correctly. If the data is not
being excluded as expected please see the Troubleshooting section below. This
completes the setup of using a disklist to exclude data.

 Expression

Quiz: what is the difference between the following entries in an exclude list?

  ./foo
  ./foo/
  ./foo/*

case 1 : directory ./foo won't be in the backup image (that's what you want)
case 2 : matches nothing (don't use it) case 3 : directory ./foo will be in the
backup image but nothing below it.

 Wildcard Expansion

Amanda has the ability to use wildcard expansion while excluding data as
implemented by tar(1). The only places that wildcard expansion is allowed is in
the "exclude" option in the dumptype, or in the exclude list. Some simple
examples:
Exclude any file or directory that ends in ".log" e.g. ppp.log, XFree86.0.log

  ./*.log

Exclude any file or directory with the string "log" e.g. logfile, maillog,
syslog, ppp.log, XFree86.0.log

  */*log*

Exclude any file or directory that starts with string "cron" and ends in ".gz"
e.g. cron.1.gz, cron.2.gz, log/cron.1.gz

  ./*cron*.gz

The question mark can be used to specify a single character. e.g. log.1, log.2,
etc

  ./log.?


 Troubleshooting

If you find that you are having trouble getting the exclude patterns to match
correctly, check out this really cool script written by John R. Jackson.
ftp://gandalf.cc.purdue.edu/pub/amanda/gtartest-exclude
This script allows you to test your patterns before placing them in an exclude
list or in the dumptype. Instructions on how to run the script are included in
the script.

 Broken gnutar?

There are versions of GNU-tar that do not correctly exclude data. Version 1.12
(plus the Amanda patches from http://www.amanda.org) are known to work
correctly, as does version 1.13.19 (and later). Anything else is questionable.

Note

UPDATE:Using GNU-tar 1.13.25 is recommended.

 The ps command is your friend.

Connect to CLIENT and run a

  ps ax | grep tar

(or

  ps ef | grep tar

on Solaris)
to see exactly how the tar command is running. Look in the output for the --
exclude or --exclude-from options in the running tar process. For example:

  $ ps ax | grep tar

  ?        R      0:37 /bin/tar --create --directory /var
  --listed-incremental /var/lib/amanda/gnutar-lists/CLIENTvar_0.new
  --sparse --one-file-system --ignore-failed-read --totals --file
  /dev/null --exclude-from=/usr/local/etc/amanda/exclude-test/exclude.var
  .

In the above output notice the string "--exclude-from=". The string following
the "=" is the exclude file currently in use. If the string was "--exclude"
then the string following the "=" is the file or directory that is currently
set to be excluded.
Contact the amanda-users mailing list: mailto://amanda-users@amanda.org.
Subscription information is available at http://www.amanda.org.

Note

Refer to http://www.amanda.org/docs/exclude.html for the current version of
this document.
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