From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gionatan Danti Subject: Re: Filesystem corruption on RAID1 Date: Sun, 20 Aug 2017 09:24:10 +0200 Message-ID: <7d0af770699948fb0ecb66185145be05@assyoma.it> References: <20170713214856.4a5c8778@natsu> <592f19bf608e9a959f9445f7f25c5dad@assyoma.it> <770b09d3-cff6-b6b2-0a51-5d11e8bac7e9@thelounge.net> <9eea45ddc0f80f4f4e238b5c2527a1fa@assyoma.it> <7ca98351facca6e3668d3271422e1376@assyoma.it> <5995D377.9080100@youngman.org.uk> <83f4572f09e7fbab9d4e6de4a5257232@assyoma.it> <59961DD7.3060208@youngman.org.uk> <784bec391a00b9e074744f31901df636@assyoma.it> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Mikael Abrahamsson Cc: Roger Heflin , Wols Lists , Reindl Harald , Roman Mamedov , Linux RAID List-Id: linux-raid.ids Il 20-08-2017 09:14 Mikael Abrahamsson ha scritto: > After a non-clean poweroff and possible mismatch now between the RAID1 > drives, and now fsck runs. It reads from the drives and fixes problem. > However because the RAID1 drives contain different information, some > of the errors are not fixed. Next time anything comes along, it might > read from a different drive than what fsck read from, and now we have > corruption. It can be even worse: if fsck reads from the disks with corrupted data and tries to repair based on these corrupted information, it can blow up the filesystem completely. In my case, heavy XFS corruption was prevented by the journal metadata checksum, which detected a corrupted journal and stopped mounting. However, some minor corruption found their ways onto the dentry/inode structures. Being a backup machine, this was not a big deal, as I simply recreated the filesystem from scratch. However, the failure mode (synced writes which were corrupted) was quite scary. Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8