- OmniPITR - omnipitr-backup-master
- IMPORTANT NOTICES
- POD ERRORS
OmniPITR - omnipitr-backup-master
- --data-dir (-D)
Where PostgreSQL datadir is located (path)
- --database (-d)
Which database to connect to to issue required SQL queries. Defaults to template1.
- --host (-h)
Which host to connect to when connecting to database to backup. Shouldn't really be changed in 99% of cases. Defaults to empty string - i.e. use UNIX sockets.
- --port (-p)
Which port to connect to when connecting to database. Defaults to 5432.
- --username (-U)
What username to use when connecting to database. Defaults to postgres.
- --xlogs (-x)
Directory that will be created. Then - will be used as source of xlogs to archive. Afterwards - it will be removed. This directory should be the same as --dst-backup for omnipitr-archive, and it shouldn't exist before running omnipitr-backup-master.
- --dst-local (-dl)
Where to copy the hot backup files on current server (you can provide many of these).
You can also specify compression per-destination. Check COMPRESSION section of the doc.
- --dst-remote (-dr)
Where to copy the hot backup files on remote server. Supported ways to transport files are rsync and rsync over ssh. Please see DESCRIPTION for more information (you can provide many of these)
You can also specify compression per-destination. Check COMPRESSION section of the doc.
- --dst-direct (-dd)
Specifies remote location to be used to store backup.
Please check DIRECT-DESTINATION part for more details.
- --temp-dir (-t)
Where to create temporary files (defaults to /tmp or $TMPDIR environment variable location)
- --log (-l)
Name of logfile (actually template, as it supports %% strftime(3) markers. Unfortunately due to the %x usage by PostgreSQL, We cannot use %% macros directly. Instead - any occurence of ^ character in log dir will be first changed to %, and later on passed to strftime.
Please note that on some systems (Solaris for example) default shell treats ^ as special character, which requires you to quote the log filename (if it contains ^ character). So you'd better write it as:
- --filename-template (-f)
Template for naming output files. Check FILENAMES section for details.
Name of file to use for pidfile. If it is specified, than only one copy of omnipitr-backup-master (with this pidfile) can run at the same time.
Trying to run second copy of omnipitr-backup-master will result in an error.
- --parallel-jobs (-PJ)
Number of parallel jobs that omnipitr-backup-master can spawn to deliver archives to remote destinations.
- --verbose (-v)
Log verbosely what is happening.
- --not-nice (-nn)
Do not use nice for compressions.
- --digest (-dg)
Digest method to use (eg MD5 or SHA-1) for checksumming. Can be a comma seperated list to use multiple digest algorithms.
For details please check CHECKSUMMING below.
- --gzip-path (-gp)
Full path to gzip program - in case you can't set proper PATH environment variable.
- --bzip2-path (-bp)
Full path to bzip2 program - in case you can't set proper PATH environment variable.
- --lzma-path (-lp)
Full path to lzma program - in case you can't set proper PATH environment variable.
- --nice-path (-np)
Full path to nice program - in case you can't set proper PATH environment variable.
- --tar-path (-tp)
Full path to tar program - in case you can't set proper PATH environment variable.
- --tee-path (-ep)
Full path to tee program - in case you can't set proper PATH environment variable.
- --rsync-path (-rp)
Full path to rsync program - in case you can't set proper PATH environment variable.
- --psql-path (-pp)
Full path to psql program - in case you can't set proper PATH environment variable.
- --ssh-path (-ssh)
Full path to ssh program - in case you can't set proper PATH environment variable.
- --shell-path (-sh)
Full path to shell to be used when calling compression/archiving/checksumming.
It is important becaus the shell needs to support >( ... ) constructions.
One of the shells that do support it is bash, and this is the default value for --shell-path. You can substitute different shell if you're sure it supports mentioned construction.
- --remote-cat-path (-rcp)
Path to cat program, to be run on remote side, when using direct destinations.
Defaults to "cat"
It will be used as command on remote machine, as:
ssh host 'cat - > /some/path/filename-from-template'
In case remote-cat-path would be given with ! as the first character, it will change the invocation on remote machine, to pass filename as argument. For example:
ssh host '/usr/local/bin/store-backup /some/path/filename-from-template'
Running this program should be done by cronjob, or manually by database administrator.
As a result of running it there are 2 files, usually named HOST-data-YYYY-MM-DD.tar and HOST-xlog-YYYY-MM-DD.tar. These files can be optionally compressed and delivered to many places - both local (on the same server) or remote (via rsync).
Which options should be given depends only on installation, but generally you will need at least:
Backup will process files in this directory.
to make sure that information is logged someplace about archiving progress
one of --dst-local or --dst-remote
to specify where to send the backup files to
Of course you can provide many --dst-local or many --dst-remote or many mix of these.
Generally omnipitr-backup-master will try to deliver WAL segment to all destinations. In case remote destination will fail, omnipitr-backup-master will retry 3 times, with 5 minute delay between tries.
In case of errors when writing to local destination - it is skipped, and error is logged.
Backups will be transferred to destinations in this order:
- 1. All local destinations, in order provided in command line
- 2. All remote destinations, in order provided in command line
Remote destination specification
omnipitr-backup-master delivers backup files to destination using rsync program. Both direct-rsync and rsync-over-ssh are supported (it's better to use direct rsync - it uses less resources due to lack of encryption.
Destination url/location should be in a format that is usable by rsync program.
For example you can use:
To allow remote delivery you need to have rsync program. In case you're using rsync over ssh, ssh program has also to be available.
In case your rsync/ssh programs are in custom directories simply set $PATH environemnt variable before starting PostgreSQL.
In some cases the overhead of creating local tarball with backup, can be too much of a burden for the system.
To make the backup generation as light on resources as possible, direct destinations have been added.
When using them, omnipitr-backup-master doesn't create any local tarballs.
Instead, output from tar (after optional compression) is sent directly to remote machine over SSH connection.
Example data flow:
tar cf - . | gzip -c - | ssh user@host 'cat - > /some/file'
In case you'd like to use compression, but do it on remote machine, you can provide --remote-cat-path starting with !, and point it to script that does compression, and stores to proper file.
For example, calling omnipitr-backup-master with following options:
-dd user@host:/var/backups -rcp '!/usr/local/bin/gzip-and-store'
Will run (a bit simplified example):
tar cf - . | ssh user@host '/usr/local/bin/gzip-and-store /var/backups/filename-from-template'
And then you can write this simplistic script as /usr/local/bin/gzip-and-store:
#!/usr/bin/env bash gzip -c - > "$1".gz
Which will make tarball on database server (it has to be run here, since that's where the files are), then transfer the tarball over ssh to remote machine, compress it there and store in /var/backups/.
Of course --dst-direct can be compressed locally, using the same syntax as with --dst-local or --dst-remote, i.e. by using "xxx=" prefix, which is described in more details in COMPRESSION part.
Every destination can have specified compression. To use it you should prefix destination path/url with compression type followed by '=' sign.
Allowed compression types:
Compresses with gzip program, used file extension is .gz
Compresses with bzip2 program, used file extension is .bz2
Compresses with lzma program, used file extension is .lzma
All compressions are done on NICE to make the operation as unobtrusive as possible.
If you want to pass any extra arguments to compression program, you can either:
make a wrapper
Write a program/script that will be named in the same way your actual compression program is named, but adding some parameters to call
use environment variables
All of supported compression programs use environment variables:
gzip - GZIP
bzip2 - BZIP2
lzma - XZ_OPT
For details - please consult manual to your choosen compression tool.
It is strongly suggest to use only 1 compression method for all destinations
OmniPITR can (since version 0.2.0) calculate checksums of created files.
To calculate the checksums, OmniPITR uses Digest Perl module (part of standard Perl distribution).
Digest module supports (now) 5 different types of checksums:
MD5 - standard md5 algorithm
SHA-1 - SHA-1 algorithm
SHA-256 - SHA-2 algorithm with hash size of 256 bits
SHA-384 - SHA-2 algorithm with hash size of 384 bits
SHA-512 - SHA-2 algorithm with hash size of 512 bits
If you'll choose to use checksums, for every type of checksum (you can specify --digest=MD5,SHA-512) there will be one additional file created, named just like data and xlog tarbals, but with __FILETYPE__ part of filename (details in FILENAMES) changed to digest name.
So, with filename template being __FILETYPE__.tar__CEXT__, gzip compression and MD5 checksumming, you will get 3 files:
It is important to understand that the checksum file is plain text, and the parts of its name that suggest tar.gz as just "leftovers" from filename template.
After creation, such checksum file can be verified with:
md5sum -c MD5.tar.gz
Naming of files for backups might be important depending on deployment.
Generally, generated filenames are named using templates, with default template being:
Within template (specified with --filename-template option) you can use following markers:
Name of server backup is made on - as reported by hostname(1) program.
It is actually required to have __FILETYPE__ - it specifies whether the file contains data (data) or xlog segments (xlog)
Based on compression algorithm choosen for given delivery. Can be empty (no compression), or contains dot (.) and literal extension associated with choosen compression program.
any ^? markers
like in strftime(3) call, but ^ will be changed to % first.
Filename template is evaluated at start, so any timestamp (^? markers) will relate to date/time of beginning of backup process.
If omnipitr-backup-master detects additional tablespaces, they will be also compressed to generated tarball.
Since the full path to the tablespace directory is important, and should be preserved, and normally tar doesn't let you store files which path starts with "/" (as it would be dangerous), omnipitr-backup-master uses the following approach:
all tablespaces will be stored in tar, and upon extraction they will be put in the directory "tablespaces", and under it - there will be the full path to the tablespace directory.
Assuming PostgreSQL PGDATA is in /var/lib/pgsql/data, and it has 3 extra tablespaces placed in:
generated DATA tarball will contain 2 directories:
data - copy of /var/lib/pgsql/data
tablespaces - which contains full directory structure leading to:
tablespaces/mnt/san/tablespace - copy of /mnt/san/tablespace
tablespaces/home/whatever/xxx - copy of /home/whatever/xxx
tablespaces/media/ssd - copy of /media/ssd
Thanks to this approach, if you'll create symlink "tablespaces" pointing to root directory (ln -s / tablespaces) before exploding tarball - all tablespace files will be created already in the correct places. This is of course not necessary, but will help if you'd ever need to recover from such backup.
Minimal setup, with copying file to local directory:
/.../omnipitr-backup-master -D /mnt/data -l /var/log/omnipitr/backup.log -dl /mnt/backups/ -x /mnt/dst-backup
Minimal setup, with compression, and copying file to remote directory over rsync:
/.../omnipitr-backup-master -D /mnt/data/ -l /var/log/omnipitr/backup.log -dr bzip2=rsync://slave/postgres/backups/ -x /mnt/dst-backup
2 remote, compressed destinations, 1 local, with auto rotated logfile, and modified filenames
/.../omnipitr-backup-master -D /mnt/data/ -l /var/log/omnipitr/backup-^Y-^m-^d.log -dr bzip2=rsync://slave/postgres/backups/ -dr gzip=backups:/mnt/hotbackups/ -dl /mnt/backups/ -f "main-__FILETYPE__-^Y^m^d_^H^M^S.tar__CEXT__" -x /mnt/dst-backup
It omnipitr-backup-master will get stopped in hard way (kill -9, or multiple ctrl-c - it is possible that it will leave database with backup mode still enabled. So, to prevent future problems with it, if you had to hard stop it - remember to connect to postgresql and issue:
omnipitr-backup-master should be running from the same system account as PostgreSQL. It is technically possible to make it work with running from another account, but it will definitely be more complicated and error-prone.
The OmniPITR project is Copyright (c) 2009-2012 OmniTI. All rights reserved.
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- Around line 477:
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