From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Litherland Subject: Re: Superblock checksum problems Date: Mon, 04 Sep 2006 16:55:47 -0400 Message-ID: <1157403347.2990.11.camel@localhost> References: <1157236610.8070.7.camel@localhost> <17659.46517.979409.131348@cse.unsw.edu.au> <1157385612.2990.4.camel@localhost> Reply-To: josh@temp123.org Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1157385612.2990.4.camel@localhost> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Mon, 2006-09-04 at 12:00 -0400, Josh Litherland wrote: > I'll test to see if they actually change values, but I can say for > certain that they are still invalid checksum, i.e. once I stop the array > I have to assemble it with -U resync to get it back online. (and it of > course rebuilds) Some real strangeness here... So, while the array was up and running (after mdadm -A -f -U resync ...) I checked the checksums: Checksum : 70c30de5 - expected 70c30db5 Checksum : 70c30df7 - expected 70c30dd7 Checksum : 70c30e09 - expected 70c30de9 Checksum : 70c30e1b - expected 70c30deb Then I unmounted, checked again... here's where things get weird Checksum : 70c352e8 - correct Checksum : 70c352fa - expected 70c352da Checksum : 70c3530c - expected 70c352ec Checksum : 70c3531e - correct Went ahead and issues mdadm -S Checksum : 70c352e8 - expected 70c352c8 Checksum : 70c352fa - expected 70c352da Checksum : 70c3530c - expected 70c352ec Checksum : 70c3531e - expected 70c352fe Now utterly perplexed, I went ahead and checked mdadm -E several more times. The actual stored checksum value isn't changing, but it's switching around to saying "expected " to saying "correct"... on ALL 4 drives at different times. Anybody have a clue what's going on here? How does mdadm (or the kernel, for that matter) decide what the checksum SHOULD be? I'll code-dive to see if I can answer that myself, but if anyones knows, I'd appreaciate a pointer. Thanks! -- Josh Litherland (josh@temp123.org)