RAID5 - nur 3 actives statt 4 (mdadm)

[eUncle]

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nas02:~# mdadm --create --verbose /dev/md1 --level=5 --raid-devices=4 /dev/mapper/sda2 /dev/mapper/sdb2 /dev/mapper/sdc2 /dev/mapper/sdd2 
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 64K
mdadm: size set to 9501824K
mdadm: array /dev/md1 started.
nas02:~# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4] 
md1 : active (auto-read-only) raid5 dm-3[4](S) dm-2[2] dm-1[1] dm-0[0]
      28505472 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]

dann hab ich das md1 gestoppt, das ganze nochmals gemacht, da wurde ich dann noch gefragt und ich bekam mehr ausgaben:

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nas02:~# mdadm --create --verbose /dev/md1 --level=5 --raid-devices=4 /dev/mapper/sda2 /dev/mapper/sdb2 /dev/mapper/sdc2 /dev/mapper/sdd2
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 64K
mdadm: /dev/mapper/sda2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 20:49:05 2010
mdadm: /dev/mapper/sdb2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 20:49:05 2010
mdadm: /dev/mapper/sdc2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 20:49:05 2010
mdadm: /dev/mapper/sdd2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 20:49:05 2010
mdadm: size set to 9501824K
Continue creating array? yes
mdadm: array /dev/md1 started.
nas02:~# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4] 
md1 : active (auto-read-only) raid5 dm-3[4](S) dm-2[2] dm-1[1] dm-0[0]
      28505472 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]

...dennoch wieder nur 3 actives



kann mir das jmd erklären?





#E#
noch'n versuch: schreib ich das ganze vorm erstellen in die mdadm.conf, starte es dann via mdadm -As /dev/md1, bekomme ich:

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mdadm: /dev/md1 has been started with 3 drives (out of 4) and 1 spare.

toll >_<

[eUncle]

mit --force wird das ganze wohl erzwungen:

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nas02:~# mdadm --create --verbose /dev/md1 --level=5 --raid-devices=4 --spare-devices=0 [b]--force[/b] /dev/mapper/sda2 /dev/mapper/sdb2 /dev/mapper/sdc2 /dev/mapper/sdd2
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 64K
mdadm: /dev/mapper/sda2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 21:24:22 2010
mdadm: /dev/mapper/sdb2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 21:24:22 2010
mdadm: /dev/mapper/sdc2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 21:24:22 2010
mdadm: /dev/mapper/sdd2 appears to be part of a raid array:
    level=raid5 devices=4 ctime=Sun Dec 26 21:24:22 2010
mdadm: size set to 9501824K
Continue creating array? yes
mdadm: array /dev/md1 started.
nas02:~# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4] 
md1 : active (auto-read-only) raid5 dm-3[3] dm-2[2] dm-1[1] dm-0[0]
      28505472 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
      	resync=PENDING

...aber immer noch auto-read-only?!

[eUncle]

lösung für das read-only: das array braucht ein fs:

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nas02:~# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4] 
md1 : active raid5 dm-3[3] dm-2[2] dm-1[1] dm-0[0]
      28505472 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
      [>....................]  resync =  0.5% (52232/9501824) finish=141.3min speed=1111K/sec