diff options
author | Bruce Momjian | 2010-08-25 23:55:54 +0000 |
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committer | Bruce Momjian | 2010-08-25 23:55:54 +0000 |
commit | 13e6d6c5da184abcdfcfc9874ad17ef09f4ea044 (patch) | |
tree | e4852bc2ebe43761287f0fc623405ec25838bc4a /doc/src | |
parent | 9389ac8928866eb4ab19b2f3892531e798e34f24 (diff) |
Remove docs for "Incrementally Updated Backups" because it was of
questionable reliability; information moved to a wiki:
http://wiki.postgresql.org/wiki/Incrementally_Updated_Backups
Backpatch to 9.0.
Diffstat (limited to 'doc/src')
-rw-r--r-- | doc/src/sgml/high-availability.sgml | 93 |
1 files changed, 1 insertions, 92 deletions
diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml index 6d45f661a5b..3674dd319f0 100644 --- a/doc/src/sgml/high-availability.sgml +++ b/doc/src/sgml/high-availability.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/high-availability.sgml,v 1.80 2010/08/24 15:22:12 momjian Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/high-availability.sgml,v 1.81 2010/08/25 23:55:54 momjian Exp $ --> <chapter id="high-availability"> <title>High Availability, Load Balancing, and Replication</title> @@ -1890,95 +1890,4 @@ LOG: database system is ready to accept read only connections </sect1> - <sect1 id="backup-incremental-updated"> - <title>Incrementally Updated Backups</title> - - <indexterm zone="high-availability"> - <primary>incrementally updated backups</primary> - </indexterm> - - <indexterm zone="high-availability"> - <primary>change accumulation</primary> - </indexterm> - - <para> - In a standby configuration, it is possible to offload the expense of - taking periodic base backups from the primary server; instead base backups - can be made by backing - up a standby server's files. This concept is generally known as - incrementally updated backups, log change accumulation, or more simply, - change accumulation. - </para> - - <para> - If we take a file system backup of the standby server's data - directory while it is processing - logs shipped from the primary, we will be able to reload that backup and - restart the standby's recovery process from the last restart point. - We no longer need to keep WAL files from before the standby's restart point. - If recovery is needed, it will be faster to recover from the incrementally - updated backup than from the original base backup. - </para> - - <para> - The procedure for taking a file system backup of the standby server's - data directory while it's processing logs shipped from the primary is: - <orderedlist> - <listitem> - <para> - Perform the backup, without using <function>pg_start_backup</> and - <function>pg_stop_backup</>. Note that the <filename>pg_control</> - file must be backed up <emphasis>first</>, as in: -<programlisting> -cp /var/lib/pgsql/data/global/pg_control /tmp -cp -r /var/lib/pgsql/data /path/to/backup -mv /tmp/pg_control /path/to/backup/data/global -</programlisting> - <filename>pg_control</> contains the location where WAL replay will - begin after restoring from the backup; backing it up first ensures - that it points to the last restartpoint when the backup started, not - some later restartpoint that happened while files were copied to the - backup. - </para> - </listitem> - <listitem> - <para> - Make note of the backup ending WAL location by calling the <function> - pg_last_xlog_replay_location</> function at the end of the backup, - and keep it with the backup. -<programlisting> -psql -c "select pg_last_xlog_replay_location();" > /path/to/backup/end_location -</programlisting> - When recovering from the incrementally updated backup, the server - can begin accepting connections and complete the recovery successfully - before the database has become consistent. To avoid that, you must - ensure the database is consistent before users try to connect to the - server and when the recovery ends. You can do that by comparing the - progress of the recovery with the stored backup ending WAL location: - the server is not consistent until recovery has reached the backup end - location. The progress of the recovery can also be observed with the - <function>pg_last_xlog_replay_location</> function, though that requires - connecting to the server while it might not be consistent yet, so - care should be taken with that method. - </para> - <para> - </para> - </listitem> - </orderedlist> - </para> - - <para> - Since the standby server is not <quote>live</>, it is not possible to - use <function>pg_start_backup()</> and <function>pg_stop_backup()</> - to manage the backup process; it will be up to you to determine how - far back you need to keep WAL segment files to have a recoverable - backup. That is determined by the last restartpoint when the backup - was taken, any WAL older than that can be deleted from the archive - once the backup is complete. You can determine the last restartpoint - by running <application>pg_controldata</> on the standby server before - taking the backup, or by using the <varname>log_checkpoints</> option - to print values to the standby's server log. - </para> - </sect1> - </chapter> |