From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: Running check and e2fsck simultaneously Date: Sun, 10 Nov 2013 16:36:35 -0600 Message-ID: <52800A73.9020401@hardwarefreak.com> References: <527FCBAF.4070208@hardwarefreak.com> <58CD4AD8-0A1E-42E8-984D-F4727EE2B8F0@gmail.com> <527FDBC1.4000009@hardwarefreak.com> <20131111073428.583b83b2@notabene.brown> Reply-To: stan@hardwarefreak.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131111073428.583b83b2@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: Ivan Lezhnjov IV , "linux-raid@vger.kernel.org" List-Id: linux-raid.ids On 11/10/2013 2:34 PM, NeilBrown wrote: > On Sun, 10 Nov 2013 13:17:21 -0600 Stan Hoeppner > wrote: > >> Also, I see little/no value in running a scheduled mdadm check on a >> RAID1 array. Any problems with RAID1 will be due to one of the disks >> beginning to fail in some mode, usually requiring sector relocation. > > I think scrubbing has value on any RAID with redundancy. That's a bit... redundant, Neil. :) > The firmware can only relocate a sector if it reads it when it is marginal > but not yet completely lost. If a sector is not read for a long time and > during that time the media degraded beyond recovery the firmware cannot do > anything. But RAID1 can - it can get it from the other device. But is a scrub required for this? Isn't this exactly what occurs during normal operation with md/RAID1? I.e. a read fails with disk error, so we grab the sector from the mirror? So what advantage is there to scrubbing md/RAID1? -- Stan