diff options
| author | Bruce Momjian <bruce@momjian.us> | 2010-02-27 01:39:46 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2010-02-27 01:39:46 +0000 |
| commit | adfb44458163bf749a2ec04db52ae88051cca498 (patch) | |
| tree | 0b26c2b434ffe704d750aeae71e0e96e6fee3f82 /doc/src | |
| parent | 4b0f822c77491264ee14a34d6dc3effbeb6d695a (diff) | |
Document ATAPI drive flush command, and mention SSD drives.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/wal.sgml | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 5f6a6eb2e18..9e9489da156 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 1.62 2010/02/20 18:28:37 momjian Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.63 2010/02/27 01:39:46 momjian Exp $ --> <chapter id="wal"> <title>Reliability and the Write-Ahead Log</title> @@ -59,8 +59,11 @@ same concerns about data loss exist for write-back drive caches as exist for disk controller caches. Consumer-grade IDE and SATA drives are particularly likely to have write-back caches that will not survive a - power failure. Many solid-state drives also have volatile write-back - caches. To check write caching on <productname>Linux</> use + power failure, though <acronym>ATAPI-6</> introduced a drive cache + flush command that some file systems use, e.g. <acronym>ZFS</>. + Many solid-state drives also have volatile write-back + caches, and many do not honor cache flush commands by default. + 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 |