From: http://linuxtoday.com/news_story.php3?ltsn=2001-08-22-004-20-NW-RH
Speed:
Despite writing some data more than once, ext3 is often faster (higher throughput) than
ext2 because ext3's journaling optimizes hard drive head motion. You can choose from three
journaling modes to optimize speed, optionally choosing to trade off some data integrity.
One mode, data=writeback, limits the data integrity guarantees, allowing old data to show
up in files after a crash, for a potential increase in speed under some circumstances.
This mode, which is the default journaling mode for most journaling file systems,
essentially provides the more limited data integrity guarantees of the ext2 file system
and merely avoids the long file system check at boot time. The second mode, data=ordered
(the default mode), guarantees that the data is consistent with the file system:
recently-written files will never show up with garbage contents after a crash. The last
mode, data=journal, requires a larger journal for reasonable speed in most cases and
therefore takes longer to recover in case of unclean shutdown, but is sometimes faster for
certain database operations. The default mode is recommended for all general-purpose
computing needs.
<snip>
* ext3 has multiple journaling modes. It can journal all file data and metadata
(data=journal), or it can journal metadata but not data (data=ordered or data=writeback).
When not journaling file data, you can choose whether to write file system data before
metadata (data=ordered; causes all metadata to point to valid data) or not handle file
data specially at all (data=writeback; file system will be consistent, but old data may
appear in files after an unclean system shutdown). This gives the administrator the power
to make the trade off between speed and file data consistency, and to tune speed for
specialized usage patterns.
So the question is what would be ideal for postgres?
--
Joseph Shraibman
jks@selectacast.net
Increase signal to noise ratio. http://www.targabot.com
