From 51a33519b0d32c8617aceb6beb259fde0c3887ac Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Mon, 10 Dec 2007 14:05:05 +0000
Subject: [PATCH] Document how to turn off disk write cache on popular
operating systems.
---
doc/src/sgml/wal.sgml | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index a1a32774343..55cd6b1d6b8 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.46 2007/11/28 15:42:31 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.47 2007/12/10 14:05:05 momjian Exp $ -->
<chapter id="wal">
<title>Reliability and the Write-Ahead Log</title>
@@ -58,8 +58,17 @@
while some are write-back, and the
same concerns about data loss exist for write-back drive caches as
exist for disk controller caches. Consumer-grade IDE drives are
- particularly likely to contain write-back caches that will not
- survive a power failure.
+ particularly likely to have write-back caches that will not survive a
+ power failure. To check write caching on <productname>Linux</> use
+ <command>hdparm -I</>; it is enabled if there is a <literal>*</> next
+ to <literal>Write cache</>. <command>hdparm -W</> can to turn off
+ write caching. On <productname>FreeBSD</> use
+ <application>atacontrol</>. (For SCSI disks use <ulink
+ url="http://sg.torque.net/sg/sdparm.html"><application>sdparm</></ulink>
+ to turn off <literal>WCE</>.) On <productname>Windows</> write caching is
+ controlled by <literal>My Computer\Open\{select disk
+ drive}\Properties\Hardware\Properties\Policies\Enable write caching on
+ the disk</>.
</para>
<para>
--
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