Date: Thu, 27 Jun 2013 10:06:45 -0700 From: Charles Swiger <cswiger@mac.com> To: Adam Vande More <amvandemore@gmail.com> Cc: =?utf-8?Q?Nikola_Pavlovi=C4=87?= <nzp@riseup.net>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Troubleshooting a gmirror disk marked broken Message-ID: <0469490B-A577-40DA-9A04-910150330E16@mac.com> In-Reply-To: <CA%2BtpaK0rT83sMcaQTsg3m31Gr2RrnZBTbDgr-sZyWAS_6fzS5w@mail.gmail.com> References: <20130627023837.GA7685@sputnjik.localdomain> <36C962B9-ABC4-45E3-AC94-46D6CEE960E1@mac.com> <CA%2BtpaK0rT83sMcaQTsg3m31Gr2RrnZBTbDgr-sZyWAS_6fzS5w@mail.gmail.com>
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Hi-- On Jun 27, 2013, at 9:58 AM, Adam Vande More <amvandemore@gmail.com> = wrote: > On Thu, Jun 27, 2013 at 10:16 AM, Charles Swiger <cswiger@mac.com> = wrote: >> If you haven't rebuilt the mirror already, running a full disk read = scan >> against both drives (ie, via "dd if=3D/dev/ad4 of=3D/dev/null bs=3D1m" = or similar) >> might be prudent. That will help identify/migrate any sectors which = are >> failing but still recoverable via ECC to the spare sectors. >=20 > I was going to say something like that too but AFAIK sectors aren't = remapped on failed reads, has to be written to(dd if=3D/dev/zero = of=3D/dev/ad4 bs=3D1m). If it were me, I make sure I had fully tested = complete backups before I broke the mirror and did that. If the drive reads a sector with ECC-correctable errors, it's supposed = to try to re-write that sector in order to fix up the ECC data. If that = write fails, it remaps. Of course, your suggestion of blanking the entire drive and restoring = from the mirror or a backup would be best, or perhaps "better short of = replacing the drive". Regards, --=20 -Chuck
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