LARGE single-system Cyrus installs?
Ian G Batten
ian.batten at uk.fujitsu.com
Tue Nov 20 10:34:12 EST 2007
On 20 Nov 07, at 1332, Michael R. Gettes wrote:
> I am wondering about the use of fsync() on journal'd file systems
> as described below. Shouldn't there be much less use of (or very
> little use) of fsync() on these types of systems? Let the journal
> layer due its job and not force it within cyrus? This would likely
> save a lot of system overhead.
fsync() forces the data to be queued to the disk. A journaling
filesystem won't usually make any difference, because no one wants to
keep an intent log of every 1 byte write, or the 100 overwrites of
the same block. If you want every write() to go to disk,
immediately, the filesystem layout doesn't really matter: it's just a
matter of disk bandwidth. Journalling filesystems are more usually
concerned with metadata consistency, so that the filesystem isn't
actively corrupt if the music stops at the wrong point in a directory
create or something.
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