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 n1M17hd9027092 for ; Sat, 21 Feb 2009 20:07:43 -0500 Received: from vms173019pub.verizon.net (vms173019pub.verizon.net [206.46.173.19]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id n1M17PcU021874 for ; Sat, 21 Feb 2009 20:07:26 -0500 Received: from [192.168.1.2] ([96.255.155.44]) by vms173019.mailsrvcs.net (Sun Java(tm) System Messaging Server 6.3-7.04 (built Sep 26 2008; 32bit)) with ESMTPA id <0KFG004JR0FUMXBT@vms173019.mailsrvcs.net> for linux-lvm@redhat.com; Sat, 21 Feb 2009 19:07:07 -0600 (CST) Message-id: <49A0A252.30803@smart.net> Date: Sat, 21 Feb 2009 19:54:42 -0500 From: "Daniel B." MIME-version: 1.0 Content-transfer-encoding: 7bit Subject: [linux-lvm] re --corelog: does synchronization re-copy all data? 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 In the LVM Administrator's Guide, at least the one at http://www.centos.org/docs/5/html/Cluster_Logical_Volume_Manager/LV_create.html , it says:" LVM maintains a small log which it uses to keep track of which regions are in sync with the mirror or mirrors. By default, this log is kept on disk, which keeps it persistent across reboots. You can specify instead that this log be kept in memory with the --corelog argument; this eliminates the need for an extra log device, but it requires that the entire mirror be resynchronized at every reboot. Does that last sentence mean that _all_ the data is recopied, or just that all _regions_ are checked and not all the data necessarily has to be copied (perhaps only change regions have to be copied, but unchanged regions don't)? More generally, can LVM perform RAID1-style mirroring with only two disks (without having to re-copy everything each boot) (and, of course, being recoverable in case either disk fails)? Thanks, Daniel -- Daniel B. dsb@smart.net