Сделал-таки имитацию ошибки, вот лог:
sda1 делал сбойным[3777928.350815] md/raid1:md0: Disk failure on sda1, disabling device.
[3777928.350816] md/raid1:md0: Operation continuing on 1 devices.
[3777928.383958] RAID1 conf printout:
[3777928.383960] — wd:1 rd:2
[3777928.383963] disk 0, wo:1, o:0, dev:sda1
[3777928.383964] disk 1, wo:0, o:1, dev:sdb1
[3777928.420261] RAID1 conf printout:
[3777928.420263] — wd:1 rd:2
[3777928.420265] disk 1, wo:0, o:1, dev:sdb1
[3778072.565288] md: unbind[sda1]
[3778072.601454] md: export_rdev(sda1)
[3778082.179715] md: export_rdev(sda1)
[3778082.287766] md: bind[sda1]
[3778082.302899] RAID1 conf printout:
[3778082.302902] — wd:1 rd:2
[3778082.302904] disk 0, wo:1, o:1, dev:sda1
[3778082.302905] disk 1, wo:0, o:1, dev:sdb1
[3778082.302948] md: recovery of RAID array md0
[3778082.302950] md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
[3778082.302951] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for recovery.
[3778082.302955] md: using 128k window, over a total of 12581816k.
[3778267.435015] md: md0: recovery done.
[3778267.585332] RAID1 conf printout:
[3778267.585335] — wd:2 rd:2
[3778267.585337] disk 0, wo:0, o:1, dev:sda1
[3778267.585339] disk 1, wo:0, o:1, dev:sdb1
Теперь sda1 помечен вторым:root# mdadm --detail /dev/md0
/dev/md0:
Version: 1.2
Creation Time: Mon Dec 10 11:16:41 2012
Raid Level: raid1
Array Size: 12581816 (12.00 GiB 12.88 GB)
Used Dev Size: 12581816 (12.00 GiB 12.88 GB)
Raid Devices: 2
Total Devices: 2
Persistence: Superblock is persistent
Update Time: Mon Mar 18 00:54:20 2013
State: clean
Active Devices: 2
Working Devices: 2
Failed Devices: 0
Spare Devices: 0
Name: rescue:0
UUID: 06492cd4:f4a865a7:9060d9a1:7f306487
Events: 64
Number Major Minor RaidDevice State
2 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1
вот что говорит ман: Also, if you have a failure, the failed device will be marked with (F) after the [#]. The spare that replaces this device will be the device with the lowest role number n or higher that is not marked (F). Once the resync operation is complete, the device's role numbers are swapped.
Как я понимаю — у вас сбоит sdb, раз нумерация дисков не меняется…
