From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Chmielewski Subject: why a bitmap file never changes? Date: Wed, 29 Aug 2007 10:45:28 +0200 Message-ID: <46D53228.4000400@wpkg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: Linux-Raid List-Id: linux-raid.ids I'm just synchronizing a local LVM volume to the remote one using md and a bitmap file, as suggested by Neil Brown ("how to synchronize two devices (RAID-1, but not really?)" thread from 15 May 2007): mdadm --build /dev/md11 --level=1 --bitmap=/root/backup-bitmap \ --write-behind --raid-disks=2 /dev/san1/backup \ --write-mostly /dev/iscsi/....../part Certainly, it takes a while to complete this operation. I noticed that the bitmap file never changes as the devices are being synced - md5sum stays always the same, no matter if resync progress was 10, 30, or 90%: # md5sum /root/backup-bitmap e8e0c4a8424dfd4d487b8facd231ce76 /root/backup-bitmap # ls -l /root/backup-bitmap -rw-r--r-- 1 root root 80676 2007-08-27 18:35 /root/backup-bitmap The date of the file is the date of creation of this array, and as I look inside, it's basically almost empty. When looking in a hex editor, zeroes (+bitm etc.)at the beginning, and than FF to the end. Is it normal? # mdadm -D /dev/md11 /dev/md11: Version : 00.90.03 Creation Time : Mon Aug 27 18:35:32 2007 Raid Level : raid1 Array Size : 658800640 (628.28 GiB 674.61 GB) Device Size : 658800640 (628.28 GiB 674.61 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 11 Persistence : Superblock is not persistent Intent Bitmap : /root/backup-bitmap Update Time : Mon Aug 27 18:39:22 2007 State : active, resyncing Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Rebuild Status : 91% complete Number Major Minor RaidDevice State 0 254 47 0 active sync /dev/dm-47 1 8 48 1 active sync writemostly /dev/sdd # cat /proc/mdstat Personalities : [raid1] md11 : active raid1 sdd[1](W) dm-47[0] 658800640 blocks super non-persistent [2/2] [UU] [==================>..] resync = 91.8% (605314368/658800640) finish=65.6min speed=13584K/sec bitmap: 315/315 pages [1260KB], 1024KB chunk, file: /root/backup-bitmap -- Tomasz Chmielewski http://wpkg.org