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| author | Bruce Momjian <bruce@momjian.us> | 2010-12-24 11:32:52 -0500 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2010-12-24 11:32:52 -0500 |
| commit | c47458529533bc88e34778818a4ce7d5c309d7a8 (patch) | |
| tree | 15aa685d811a615bf005599cf71834d7b3b70c8a | |
| parent | 554b00cdaba5aac12e53f41214dad4d8a95fc6d4 (diff) | |
Backpatch to 9.0 a doc mention that a BBU does not prevent partial page
writes.
| -rw-r--r-- | doc/src/sgml/wal.sgml | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 54fcf93954d..e212ddf16c0 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -167,10 +167,12 @@ <productname>PostgreSQL</> periodically writes full page images to permanent WAL storage <emphasis>before</> modifying the actual page on disk. By doing this, during crash recovery <productname>PostgreSQL</> can - restore partially-written pages from WAL. If you have a battery-backed disk - controller or file-system software that prevents partial page writes - (e.g., ZFS), you can safely turn off this page imaging by turning off the - <xref linkend="guc-full-page-writes"> parameter. + restore partially-written pages from WAL. If you have file-system software + that prevents partial page writes (e.g., ZFS), you can turn off + this page imaging by turning off the <xref + linkend="guc-full-page-writes"> parameter. Battery-Backed Unit + (BBU) disk controllers do not prevent partial page writes unless + they guarantee that data is written to the BBU as full (8kB) pages. </para> </sect1> |