Date: Mon, 4 Jun 2012 17:54:03 -0500 From: Dustin Wenz <dustinwenz@ebureau.com> To: freebsd-fs@freebsd.org Subject: Can mps drop a failing device from bus? Message-ID: <5532CFFB-F943-4D9E-9722-7FB9C8A9F82A@ebureau.com>
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I asked this question back in April on the stable list with no response = ( = http://lists.freebsd.org/pipermail/freebsd-stable/2012-April/067305.html = ). I've now been seeing the same behavior on 9.0-release, and I thought = it would be good to ask again here. There is a failure mode for SATA disks (Seagate Barracuda ST3000DM001 = disks, in this case) that the mps driver doesn't handle very well. If a = disk is slow to respond, or is unresponsive altogether, I'd like it to = be removed from the bus and degrade the zpool that it's a part of. The way things are now, mps will just report a lot of "SCSI command = timeout on device" messages. Any I/O on the affected zpools will hang = for an excessive amount of time (sometimes forever). We typically = configure our storage volumes as a pool of mirrors, with the expectation = that availability will be maintained if any redundant disk(s) should = fail. Unfortunately, availability is actually made *worse* on = highly-redundant mirrors when mps won't give up on an unresponsive = device. It's possible that I'm overlooking an obvious solution, or some relevant = configuration options for the driver. Can anyone offer some insight on = this? Thanks, - .Dustin
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