Date: Wed, 27 Oct 2010 11:11:24 +0100 From: Bruce Cran <bruce@cran.org.uk> To: perryh@pluto.rain.com Cc: freebsd-hackers@freebsd.org, ivoras@freebsd.org Subject: Re: fsync(2) manual and hdd write caching Message-ID: <20101027111124.00007450@unknown> In-Reply-To: <4cc7ea44.ApOaxS8Xr4Sxu%2B0x%perryh@pluto.rain.com> References: <20101026213618.GA3013@freebsd.org> <ia7nln$piv$1@dough.gmane.org> <4cc7ea44.ApOaxS8Xr4Sxu%2B0x%perryh@pluto.rain.com>
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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
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