mdadm: hot remove falhou paira …

Meu RAID1 está degradado e preciso replace / dev / sdb. No entanto, eu poderia maircair / dev / sdb5 (no / dev / md1) como crashdo e removido, mas não posso fazer o mesmo com / dev / sdb1 (/ dev / md0 que está montado em /):

root@kes:~# mdadm /dev/md0 --fail /dev/sdb1 mdadm: set /dev/sdb1 faulty in /dev/md0 root@kes:~# mdadm --detail /dev/md0 /dev/md0: Version : 00.90 Creation Time : Wed Apr 7 03:00:39 2010 Raid Level : raid1 Array Size : 975185536 (930.01 GiB 998.59 GB) Used Dev Size : 975185536 (930.01 GiB 998.59 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Mon Feb 13 12:27:41 2012 State : active, degraded Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spaire Devices : 0 UUID : cdc01e79:774eba08:ade2cb46:d0df0469 (local to host kes) Events : 0.67569047 Number Major Minor RaidDevice State 0 8 1 0 active sync /dev/sda1 2 8 17 1 faulty spaire rebuilding /dev/sdb1 root@kes:~# mdadm /dev/md0 --remove /dev/sdb1 mdadm: hot remove failed for /dev/sdb1: Device or resource busy 

Então, o que estou fazendo de errado?