From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Kraus Subject: Re: Timeout question Date: Wed, 06 Nov 2013 07:49:03 +0100 Message-ID: <5279E65F.8020209@hanswkraus.com> References: <5277FE65.8050001@hanswkraus.com> <5278220C.3060607@turmel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5278220C.3060607@turmel.org> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi Phil, thanks. Debian does already a scrub every first Sunday of a month. Upgrading to a Raid6 is planned when I have the money for the disk(s). I already encountered a second failure during rebuild of a raid5, (that was the trigger for the backup solution), so I'm very aware of that possibility. My main storage is already a raid6, on NAS drives. Kind regards, Hans Am 04.11.2013 23:39, schrieb Phil Turmel: > [...] >> Afterwards, these four raid0 are the members of a raid5. The idea >> behind this is to be able to replace the raid0 with single 4 TB drives. >> Now comes my question: Do I need to care for timeouts of the raid0, and >> if so, how do I do that? The following doesn't work: >> for x in md??; do >> /bin/echo $x >> "--------------------------------------------------------------------------" >> >> echo 180 >/sys/block/$x/device/timeout || echo >> "/sys/block/$x/device/timeout not available" >> /bin/echo >> "-------------------------------------------------------------------------------" >> >> done > > No. The timeouts only matter on the physical devices. MD doesn't have > a timeout as it isn't a physical driver. What you have appears to be > correct. > > Make sure you also have a "check" scrub in a cron job for everything > greater than raid0. (Interval can vary--I use weekly.) And follow up > on the cron job with a report of all mismatch-cnt values. > > For large capacities with consumer drives (~8TB or more, IMHO), you > should seriously consider raid6. The probability of an unrecoverable > read error interrupting a raid5 rebuild after a drive failure is > shockingly high. > > HTH, > > Phil