diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 7b50bddd04c71069a2a128fd72dc4b59f4bc3dae..e7980b386e9920b3c24e018c8683cb8c5b8e245d 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -69,26 +69,57 @@ </para> <para> - 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</> to turn off - write caching. On <productname>FreeBSD</> use - <application>atacontrol</>. (For SCSI disks use <ulink - url="http://sg.danny.cz/sg/sdparm.html"><application>sdparm</></ulink> - to turn off <literal>WCE</>.) 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.) 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</>. Also on Windows, <literal>fsync</> and - <literal>fsync_writethrough</> never do write caching. The - <literal>fsync_writethrough</> option can also be used to disable - write caching on <productname>MacOS X</>. - </para> + 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> <para> Many file systems that use write barriers (e.g. <acronym>ZFS</>,