Date: Thu, 30 Jul 2015 15:22:22 +0000 From: "Pokala, Ravi" <rpokala@panasas.com> To: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: getting a disk structure given a device name Message-ID: <D1DF8804.13F03F%rpokala@panasas.com>
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>Date: Wed, 29 Jul 2015 23:31:03 +0000 >From: Raviprakash Darbha <rdarbha@juniper.net> >To: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> >Cc: Steve Kiernan <stevek@juniper.net>, Simon Gerraty > <sjg@juniper.net> >Subject: getting a disk structure given a device name >Message-ID: <F8ED1BDC-D8DA-458B-A652-B125183F27CB@juniper.net> >Content-Type: text/plain; charset=3D"us-ascii" > >Hello All=20 > >I am trying to write a filter driver for the ata block on freebsd 6.2 to >simulate failed reads and writes. We originally did something like that at Panasas, but by hacking ata(4) and ad(4) directly. :-P Later on, we created a GEOM class to do error injection. Currently, I prefer using the WRITE_UNCORRECTABLE48 command, to tell the drive to actually return errors on subsequent reads. That has the benefit of being indistinguishable from an actual read failure - the drive spends the time to do error recovery, and sends the actual error code back. -Ravi
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