From: Tejun Heo <htejun@gmail.com>
To: ric@emc.com
Cc: Mark Lord <liml@rtr.ca>,
jeff@garzik.org, linux-ide@vger.kernel.org,
alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCHSET #upstream] libata: improve FLUSH error handling
Date: Fri, 28 Mar 2008 23:52:15 +0900 [thread overview]
Message-ID: <47ED061F.2070701@gmail.com> (raw)
In-Reply-To: <47ECF47A.2040508@emc.com>
Ric Wheeler wrote:
> I think that is a really important knob to have. Not just for RAID
> systems, but we use the FLUSH_CACHE on systems without barriers mainly
> when we power down & do the unmounts, etc.
>
> If you hit a bad block during power down of a laptop, I can image that
> have a worst case of (30?) seconds is infinitely better than multiple
> minutes ;-)
Fully finishing FLUSH CACHE requires command repetition. Not fully
finishing FLUSH CACHE on shutdown means sure data loss. Given that
FLUSH CACHE failure is very rare and it's repeatedly retried if and only
if the device actively indicates failure, I'm not too sure. Also note
that if FLUSH CACHE fails, you cannot even trust the FS journal. Things
can get silently corrupt.
--
tejun
next prev parent reply other threads:[~2008-03-28 14:59 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-27 10:14 [PATCHSET #upstream] libata: improve FLUSH error handling Tejun Heo
2008-03-27 10:14 ` [PATCH 1/4] libata: make ata_tf_to_lba[48]() generic Tejun Heo
2008-04-04 7:45 ` Jeff Garzik
2008-03-27 10:14 ` [PATCH 2/4] libata: implement ATA_QCFLAG_RETRY Tejun Heo
2008-03-27 10:14 ` [PATCH 3/4] libata: kill unused ata_flush_cache() Tejun Heo
2008-03-27 10:14 ` [PATCH 4/4] libata: improve FLUSH error handling Tejun Heo
2008-04-04 7:46 ` Jeff Garzik
2008-03-27 10:23 ` Debug patch to induce errors on FLUSH Tejun Heo
2008-03-27 14:24 ` [PATCHSET #upstream] libata: improve FLUSH error handling Mark Lord
2008-03-27 14:35 ` Mark Lord
2008-03-27 15:31 ` Alan Cox
2008-03-27 18:01 ` Ric Wheeler
2008-03-28 1:57 ` Tejun Heo
2008-03-28 2:33 ` Mark Lord
2008-03-28 13:36 ` Ric Wheeler
2008-03-28 14:52 ` Tejun Heo [this message]
2008-03-28 14:53 ` Ric Wheeler
2008-03-28 15:16 ` Alan Cox
2008-03-28 16:57 ` Ric Wheeler
2008-03-28 16:04 ` Mark Lord
2008-03-27 17:53 ` Ric Wheeler
2008-03-27 18:52 ` Jeff Garzik
2008-03-27 20:23 ` Ric Wheeler
2008-03-28 7:46 ` Andi Kleen
2008-03-28 8:30 ` Tejun Heo
2008-03-28 8:48 ` Andi Kleen
2008-03-28 8:53 ` Tejun Heo
2008-03-27 17:51 ` Ric Wheeler
2008-03-27 18:53 ` Jeff Garzik
2008-03-27 22:00 ` Alan Cox
2008-03-28 2:02 ` Tejun Heo
2008-03-28 9:48 ` Alan Cox
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