From: Asdo Subject: Re: Sync does not flush to disk!? Date: Fri, 08 Jun 2012 13:39:41 +0200 Message-ID: <4FD1E47D.2050908@shiftmail.org> References: <4FD1CB8A.9080805@shiftmail.org> Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: linux-raid , linux-ext4@vger.kernel.org To: Asdo Return-path: Received: from blade3.isti.cnr.it ([194.119.192.19]:4946 "EHLO blade3.isti.cnr.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968Ab2FHLjf (ORCPT ); Fri, 8 Jun 2012 07:39:35 -0400 In-reply-to: <4FD1CB8A.9080805@shiftmail.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 06/08/12 11:53, Asdo wrote: > ..... > Then I tried to do : > > for i in /dev/md? /dev/sda /dev/sdb ; do blockdev --flushbufs $i ; done > .... > and NOW it is seeing the changes. After some further tests: Flushbuf'ing just the MD devices only, generated an even more intermediate situation in which the file being changed assumed garbage content coming from another old file. Flushbufing just /dev/sda /dev/sdb has worked a few times I tried. I'm not sure that it is enough in general. Flushbufing everything appears to work reliably. Still I am puzzled. Wasn't "sync" from bash enough to commit to disk even in case of power failure? Or is there any chance that KVM "sees" a version of sda and sdb which is actually *older* than the actual content on the platters? Thank you