From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m9S2TnOc005213 for ; Mon, 27 Oct 2008 22:29:49 -0400 Received: from mail.unpatched.net (mail.unpatched.net [80.179.151.65]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id m9S2SCf3001676 for ; Mon, 27 Oct 2008 22:28:13 -0400 Received: from [192.168.10.98] (localhost [127.0.0.1]) by mail.unpatched.net (Postfix) with ESMTP id 754F5D40DA for ; Tue, 28 Oct 2008 04:31:26 +0200 (IST) Message-ID: <490678BE.1070700@hidden.domain.name> Date: Tue, 28 Oct 2008 04:28:14 +0200 From: Yoav MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [linux-lvm] mirror and snapshot incompatible 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: linux-lvm@redhat.com According to lvcreate, a snapshot of a mirrored volume cannot be created ("Snapshots and mirrors may not yet be mixed"). However, devmapper does not seem to have the same limitation when used directly (not through lvm). Is there a current reason for lvcreate to enforce this rather harsh limitation? What are the risks I'm taking by manually creating a dm-snapshot from a dm-mirror device? (of course I'm also replacing the dm-mirror device with a snapshot-origin of the actual dm-mirror device). If there is an actual reason for preventing this, what is the suggested way to consistently backup a mirror volume? Is there a way to temporarily take one of the mirror "legs" (mimage devices) offline in order to back it up, and resync it later? Yoav