Date: Sat, 24 Nov 2007 00:47:11 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Julian Elischer <julian@elischer.org> Cc: Alan Cox <alc@cs.rice.edu>, FreeBSD Current <current@freebsd.org> Subject: Re: suggested ways of faking EIO? Message-ID: <20071124064711.GB4226@dan.emsphone.com> In-Reply-To: <4747A9B8.9080403@elischer.org> References: <4747A9B8.9080403@elischer.org>
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In the last episode (Nov 23), Julian Elischer said: > I need to make physio make a request from disk, and have the request > come back asynchronously with an EIO. > > I have tried just reading some distance past the end of a partition, > but I'm not totally convinced that it acts exactly like as if I'd > tried to read a bad sector. Since geom has been added, the legality > of a read needs to be tested in the geometry layer, so I suppose it > must come back asynchronously, as that is no longer directly executed > through function calls but is it really the same as a disk failure? > > Anyone done this? or does anyone have a disk with a known bad sector > I can try my test case on? :-) The geom NOP module can fail a given percentage of I/O with whatever error number you choose. You could hack g_nop.c to make it fail on a given sector instead. -- Dan Nelson dnelson@allantgroup.com
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