Date: Sun, 31 Oct 2010 13:20:16 -0500 From: "James R. Van Artsdalen" <james-freebsd-fs2@jrv.org> To: Thomas Zander <thomas.e.zander@googlemail.com> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS inresponsive. Message-ID: <4CCDB360.50609@jrv.org> In-Reply-To: <AANLkTi=vKSC_wULSzd9k2hF-gDTVeseqyzWrKHsAOMd2@mail.gmail.com> References: <BE2EF896-4990-4A75-9DD4-B0534DFE0B71@pean.org> <20101031104209.771cc47e@r500.local> <AANLkTi=vKSC_wULSzd9k2hF-gDTVeseqyzWrKHsAOMd2@mail.gmail.com>
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Thomas Zander wrote: > Same here, same setup. ZFS, GELI, USB. It is not a good idea to use USB disks with ZFS. It can cause pool loss. Many (most?) USB enclosures use USB<->SATA chips that discard the SYNC/FLUSH command to the disk. As a result this opens a window of time where disk writes might be reordered in a way that cause the ZFS structures to become corrupted. There's no problem in normal operation but there may be a failure if there is a power loss. The log entries in Fabian's note look like a USB SYNC/FLASH failure to me - that USB enclosure should not be used with ZFS. At one time there was talk of "deferred reallocation" in ZFS which would deal with broken USB enclosures but I don't know if Sun ever got around to this.
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