From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (mx1.redhat.com [172.16.48.31]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n3GDwrEQ009968 for ; Thu, 16 Apr 2009 09:58:53 -0400 Received: from mail.comfortechassist.com (mail.comfortechassist.com [206.123.115.188]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n3GDwXPf022756 for ; Thu, 16 Apr 2009 09:58:33 -0400 Received: from foxtrot.brunson.com (c-76-120-85-88.hsd1.co.comcast.net [76.120.85.88]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.comfortechassist.com (Postfix) with ESMTP id EED207C075 for ; Thu, 16 Apr 2009 07:54:18 -0600 (MDT) Message-ID: <49E73987.3040604@brunson.com> Date: Thu, 16 Apr 2009 07:58:31 -0600 From: Eric Brunson MIME-Version: 1.0 Subject: Re: [linux-lvm] Simulating LVM Mirror Failure and recovery References: <29070.706.qm@web94806.mail.in2.yahoo.com> <49E71F9D.3010401@sivell.com> <20090416125403.GU7843@agk.fab.redhat.com> <49E7345B.1040002@brunson.com> In-Reply-To: <49E7345B.1040002@brunson.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development On 04/16/2009 07:36 AM, Eric Brunson wrote: > On 04/16/2009 06:54 AM, Alasdair G Kergon wrote: >> On Thu, Apr 16, 2009 at 07:07:57AM -0500, vu pham wrote: >>> yogeen honnavar wrote: >>>> Dear users, >>>> dd if=/dev/zero of=/dev/vg1/lv1 count=10 >>>> as per the redhat guide this should result in mirror leg failure >>>> and any >> >> Can you provide the reference - where does it say this? >> >> Alasdair > > I believe this is the reference. > > http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Cluster_Logical_Volume_Manager/mirrorrecover.html > > > Their example may be in error. > > Upon review, I think it's correct, but worded awkwardly: In this example, the primary leg of the mirror |/dev/sda1| fails. Any write activity to the mirrored volume causes LVM to detect the failed mirror. When this occurs, LVM converts the mirror into a single linear volume. In this case, to trigger the conversion, we execute a |dd| command [root@link-08 ~]#*|dd if=/dev/zero of=/dev/vg/groupfs count=10|* 10+0 records in 10+0 records out I believe the dd is not to cause the failure, it's simply to generate write activity to the volume group after the mirror leg has been caused to fail through other means not documented. Anyone else think that's the case? e. > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/