These caches can typically be disabled; however, the method for doing

this varies by operating system and drive type:

</para>

<itemizedlist>

<listitem>

<para>

On <productname>Linux</>, IDE drives can be queried using

<command>hdparm -I</command>; write caching is enabled if there is

a <literal>*</> next to <literal>Write cache</>. <command>hdparm -W</>

can be used to turn off write caching. SCSI drives can be queried

using <ulink url="http://sg.danny.cz/sg/sdparm.html"><application>sdparm</></ulink>.

for SCSI drives. Use <command>sdparm --get=WCE</command> to check

whether the write cache is enabled and <command>sdparm --clear=WCE</>

to disable it.

</para>

</listitem>

<listitem>

<para>

On <productname>FreeBSD</>, IDE drives can be queried using

<command>atacontrol</command>, and SCSI drives using

<command>sdparm</command>.

</para>

</listitem>

<listitem>

<para>

On <productname>Solaris</>, the disk write cache is controlled by

<ulink url="http://www.sun.com/bigadmin/content/submitted/format_utility.jsp"><literal>format -e</></ulink>.

(The Solaris <acronym>ZFS</> file system is safe with disk write-cache

enabled because it issues its own disk cache flush commands.)

</para>

</listitem>

<listitem>

<para>

On <productname>Windows</>, if <varname>wal_sync_method</> is

<literal>open_datasync</> (the default), write caching is disabled

by unchecking <literal>My Computer\Open\{select disk drive}\Properties\Hardware\Properties\Policies\Enable write caching on the disk</>.

Alternatively, set <varname>wal_sync_method</varname> to <literal>fsync</> or <literal>fsync_writethrough</>, which never do write caching.

</para>

</listitem>

<listitem>

<para>

On <productname>MacOS X</productname>, write caching can be disabled by

setting <varname>wal_sync_method</> to <literal>fsync_writethrough</>.

</para>

</listitem>

</itemizedlist>