From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx02.extmail.prod.ext.phx2.redhat.com [10.5.110.6]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id oAUDDpP5023278 for ; Tue, 30 Nov 2010 08:13:51 -0500 Received: from atl.turmel.org (atl.turmel.org [74.117.157.138]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id oAUDDflT005286 for ; Tue, 30 Nov 2010 08:13:42 -0500 Message-ID: <4CF4F85C.1020806@turmel.org> Date: Tue, 30 Nov 2010 08:13:00 -0500 From: Phil Turmel MIME-Version: 1.0 References: <4CF3F7A0.2080108@rjl.com> <4CF4A472.20107@rjl.com> In-Reply-To: Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Q: LVM over RAID, or plain disks? A:"Yes" = best of both worlds? 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" To: hansbkk@gmail.com Cc: linux-raid@vger.kernel.org, Nataraj , linux-lvm@redhat.com Hi Hans, (?) On 11/30/2010 02:34 AM, hansbkk@gmail.com wrote: > On Tue, Nov 30, 2010 at 2:14 PM, Nataraj wrote: >>> TopRAID1's LVM is likely to be running over a RAID6 set , so I'm not >>> depending on the TopRAID mirroring for reliability, just using it for >>> the above volume cloning. >> >> Your raid 1 backups won't mirror any snapshots of your LV's unless you >> specifically setup mirroring of the snapshots after they exist. > > Ah, getting clearer to me, I was thinking I'd be mirroring the LV > itself, but you're right, taking a snapshot and mirroring that is a > much better idea. I think you are making this overly complex, insisting on a RAID1 operation to backup from on filer to the other. Consider having each disk on filer #2 configured as a single LVM PV/VG, so it can stand alone in a rotation. The try the alternate below. > So here's a summary of steps, please confirm: > - create a snapshot of a given volume Here's where you are over-complicating things: > - create a new RAID1 mdN between that and a physical partition (blank?) > - let that get sync'd up > - break the RAID (fail the partition?), remove the drive As an alternate, with simpler recovery semantics: Create matching LV on non-RAID PV/VG on filer #2 dd + netcat + dd or other technique to dup the snapshot on filer #1 to filer #2 > - delete the snapshot Now, you have a single disk in your backup set that can be mounted on either filer, and either copied back into service, or in an emergency, used directly (live) in filer #1. This approach also gives you the *option* to implement the backup transfer with file system conversions, compression, free space removal, or any other administrative adjustments you need. A RAID mirror can only duplicate the raw block device. HTH, Phil From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Turmel Subject: Re: [linux-lvm] Q: LVM over RAID, or plain disks? A:"Yes" = best of both worlds? Date: Tue, 30 Nov 2010 08:13:00 -0500 Message-ID: <4CF4F85C.1020806@turmel.org> References: <4CF3F7A0.2080108@rjl.com> <4CF4A472.20107@rjl.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: hansbkk@gmail.com Cc: Nataraj , linux-raid@vger.kernel.org, linux-lvm@redhat.com List-Id: linux-raid.ids Hi Hans, (?) On 11/30/2010 02:34 AM, hansbkk@gmail.com wrote: > On Tue, Nov 30, 2010 at 2:14 PM, Nataraj wrote: >>> TopRAID1's LVM is likely to be running over a RAID6 set , so I'm not >>> depending on the TopRAID mirroring for reliability, just using it for >>> the above volume cloning. >> >> Your raid 1 backups won't mirror any snapshots of your LV's unless you >> specifically setup mirroring of the snapshots after they exist. > > Ah, getting clearer to me, I was thinking I'd be mirroring the LV > itself, but you're right, taking a snapshot and mirroring that is a > much better idea. I think you are making this overly complex, insisting on a RAID1 operation to backup from on filer to the other. Consider having each disk on filer #2 configured as a single LVM PV/VG, so it can stand alone in a rotation. The try the alternate below. > So here's a summary of steps, please confirm: > - create a snapshot of a given volume Here's where you are over-complicating things: > - create a new RAID1 mdN between that and a physical partition (blank?) > - let that get sync'd up > - break the RAID (fail the partition?), remove the drive As an alternate, with simpler recovery semantics: Create matching LV on non-RAID PV/VG on filer #2 dd + netcat + dd or other technique to dup the snapshot on filer #1 to filer #2 > - delete the snapshot Now, you have a single disk in your backup set that can be mounted on either filer, and either copied back into service, or in an emergency, used directly (live) in filer #1. This approach also gives you the *option* to implement the backup transfer with file system conversions, compression, free space removal, or any other administrative adjustments you need. A RAID mirror can only duplicate the raw block device. HTH, Phil