>From what I read from the internet, write-intent bitmap decreases raid
performance and provides more stability. But in my situation, it also
increases raid performance dramatically!
My RAID5 write speed without write-intent bitmap is 90MB/s, and is
increased to 200MB/s after enabling internal write-intent bitmap. I
use ext4 filesystem on this raid array. The following is my RAID5
array information:
# mdadm --detail /dev/md0
/dev/md0:
Version : 1.0
Creation Time : Mon Nov 16 02:46:50 2009
Raid Level : raid5
Array Size : 10255968576 (9780.85 GiB 10502.11 GB)
Used Dev Size : 1465138368 (1397.26 GiB 1500.30 GB)
Raid Devices : 8
Total Devices : 8
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Wed Jun 30 03:51:56 2010
State : active
Active Devices : 8
Working Devices : 8
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
Name : AOpen:00
UUID : abb2242c:6a250d29:df65e52b:426f4ed9
Events : 405636
Number Major Minor RaidDevice State
4 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1
5 8 81 4 active sync /dev/sdf1
6 8 97 5 active sync /dev/sdg1
7 8 113 6 active sync /dev/sdh1
8 8 129 7 active sync /dev/sdi1
--
Shaochun Wang <scwang@xxxxxxxxx>
Jabber: fungusw@xxxxxxxxxx
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