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Document that non-data journaling is a recommended mount option.

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Bruce Momjian 2008-12-06 21:34:27 +00:00
parent 7a567d9407
commit 31076c8beb
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doc/src/sgml/wal.sgml
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<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.53 2008/05/02 19:52:37 tgl Exp $ --> <!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.54 2008/12/06 21:34:27 momjian Exp $ -->
<chapter id="wal"> <chapter id="wal">
<title>Reliability and the Write-Ahead Log</title> <title>Reliability and the Write-Ahead Log</title>
@ -135,6 +135,21 @@
roll-forward recovery, also known as REDO.) roll-forward recovery, also known as REDO.)
</para> </para>
<tip>
<para>
Because <acronym>WAL</acronym> restores database file
contents after a crash, it is not necessary to use a
journaled filesystem; in fact, journaling overhead can
reduce performance. For best performance, turn off
<emphasis>data</emphasis> journaling as a filesystem mount
option, e.g. use <literal>data=writeback</> on Linux.
Meta-data journaling (e.g. file creation and directory
modification) is still desirable for faster rebooting after
a crash.
</para>
</tip>
<para> <para>
Using <acronym>WAL</acronym> results in a Using <acronym>WAL</acronym> results in a
significantly reduced number of disk writes, because only the log significantly reduced number of disk writes, because only the log