Richard Huxton wrote:
> > If the answer is "yes", then I understand the use of FSYNC.
> >
> > If the answer is "no", then i don't see the point in using FSYNC at all.
>
> The answer is "yes" providing:
> 1. Your hardware didn't suffer a failure during the outage.
> 2. Your disks don't like to the operating-system.
>
> The second point is important - some disks have write-cache enabled and report
> "done" when data is written to the cache not the platter. Google for
> discussion.
The problem here is whether write-cache is enabled _and_ the disk drive
doesn't use some trick of using the disk drive rotational energy to
ensure that the write cache gets flushed to disk on a power failure, or
perhaps uses some short-term battery to make sure the data gets flushed.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
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