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Date: Wed, 27 Oct 2010 11:11:24 +0100
From: Bruce Cran <bruce@cran.org.uk>
To: perryh@pluto.rain.com
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Cc: freebsd-hackers@freebsd.org, ivoras@freebsd.org
Subject: Re: fsync(2) manual and hdd write caching
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On Wed, 27 Oct 2010 02:00:51 -0700
perryh@pluto.rain.com wrote:

> Short of mounting synchronously, with the attendant performance
> hit, would it not make sense for fsync(2) to issue ATA_FLUSHCACHE
> or SCSI "SYNCHRONIZE CACHE" after it has finished writing data
> to the drive?  Surely the low-level capability to issue those
> commands must already exist, else we would have no way to safely
> prepare for power off.

mounting synchronously won't help, will it? As I understand it that
just makes sure that data is sent straight to disk and not left in
memory; the data will still be stored in the HDD cache for a
while.

-- 
Bruce Cran