From c47458529533bc88e34778818a4ce7d5c309d7a8 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Fri, 24 Dec 2010 11:32:52 -0500 Subject: [PATCH] Backpatch to 9.0 a doc mention that a BBU does not prevent partial page writes. --- doc/src/sgml/wal.sgml | 10 ++++++---- 1 file 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 @@ PostgreSQL periodically writes full page images to permanent WAL storage before modifying the actual page on disk. By doing this, during crash recovery 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 - 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 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. -- 2.39.5