红帽子5.3 raid5的问题

磁盘坏了之后raid启动不起来

[root@imegaware dev]# mdadm -E /dev/sdb
/dev/sdb:
Magic : a92b4efc
Version : 00.90.00
UUID : add64b93:2c5a2503:4c2ca768:9e35d09f
Creation Time : Tue Jun 15 16:15:01 2010
Raid Level : raid5
Used Dev Size : 1465138496 (1397.26 GiB 1500.30 GB)
Array Size : 4395415488 (4191.79 GiB 4500.91 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0

Update Time : Wed Nov 23 13:31:09 2011
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 2
Spare Devices : 0
Checksum : 5ff784d2 - correct
Events : 0.10572

Layout : left-symmetric
Chunk Size : 64K

Number Major Minor RaidDevice State
this 0 8 16 0 active sync /dev/sdb

0 0 8 16 0 active sync /dev/sdb
1 1 0 0 1 faulty removed
2 2 8 48 2 active sync /dev/sdd
3 3 0 0 3 faulty removed