From mboxrd@z Thu Jan 1 00:00:00 1970 From: Piergiorgio Sartor Subject: Reliability of bitmapped resync Date: Mon, 23 Feb 2009 20:40:19 +0100 Message-ID: <20090223194019.GA3488@lazy.lzy> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi all, I've a strange issue. I've a PC with 2 HDs in RAID-10 f2 with bitmap. There are actually 3 md devices, boot, swap and root. It happens that one SATA cable is/was flaky, so sometimes, at boot, /dev/sdb does not show up. The RAID starts in degraded mode, tracking the writes in the bitmap. On the next reboot, /dev/sdb is again there, so it is possible to re-add it. The md device resyncs what is to be resynced, very quickly, due to the bitmap. Later, if I run a check, usually a lot of mismatches show up. After repair (or add) further checks return zero mismatches. Without boot failure, no mismatches showed up after check. On a different PC, with same setup, but good cables, something similar happened. I tried, just for testing, to fail-remove-writeSomething-reAdd one HD, a then run a check. This was also returned some (few) mismatches. Now, this test I did not repeat, so I cannot say this was always the case. Nevertheless I'm a bit concerned. Is this behaviour somehow expected? Is there something special to take into account when removing and re-adding a RAID component? Thanks a lot in advance, bye, -- piergiorgio