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
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