Date: Fri, 2 Feb 2007 08:13:48 -0800 (PST) From: mjacob@freebsd.org To: Nate Lawson <nate@root.org> Cc: scsi@freebsd.org Subject: Re: cvs commit: src/sys/cam/scsi scsi_da.c Message-ID: <20070202080329.L17850@ns1.feral.com> In-Reply-To: <45C2E7DB.30204@root.org> References: <20070123173026.E692416A4CD@hub.freebsd.org> <45B65710.4060607@root.org> <20070123105009.G41619@ns1.feral.com> <45B67401.9070102@samsco.org> <20070201150111.B77236@ns1.feral.com> <45C27965.1010803@samsco.org> <45C2E7DB.30204@root.org>
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> I think Windows actually never runs SYNC_CACHE unless you select "detach > device". Maybe for pluggable devices, but otherwise Windows uses SYNC_CACHE and FUA quite freely (and correctly). I'm uncomfortable with the notion that there is uncommitted data present in a device after a close that can be lost due to power lossage (or unpluggage). From a user application or filesystem point of view, this is an axiom violation that no OS should ever allow. >From a silly semantic point of view to get around this, we should still support and require SYNC_CACHE on close except where devices don't support it (and any device that hangs on a SYNC_CACHE doesn't support it- period). On detach, devices that still need to have data commited via an opcode that looks remarkably like SYNC_CACHE can and should have that happen- with all the infrastructure changes that go along with allowing devices to be detached (w/o complaint) with a live command. Or have I missed something it what you're suggesting? -matt
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