mdadm puzzle
I can't get mdadm to build a raid5 device from 4 sata drives.
The relevant partitions seem to be there, viz:
cat /proc/partitions
major minor #blocks name
8 0 78150744 sda
8 1 78148161 sda1
8 16 156290904 sdb
8 17 156288321 sdb1
8 32 156290904 sdc
8 33 156288321 sdc1
8 48 156290904 sdd
8 49 156288321 sdd1
8 64 156290904 sde
8 65 156288321 sde1
8 80 78150744 sdf
8 81 78148161 sdf1
9 0 78148096 md0
and particularly:
fdisk /dev/sdc
The number of cylinders for this disk is set to 19457.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): p
Disk /dev/sdc: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 1 19457 156288321 fd Linux raid autodetect
But when I try to build the raid:
mdadm --create /dev/md1 --level=5 --raid-devices=4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1
mdadm: error opening /dev/md1: No such file or directory
and mdadm scan shows:
echo 'DEVICE /dev/sd[a-f]1' > /etc/mdadm/mdadm.conf
mdadm --examine --scan --config=/etc/mdadm/mdadm.conf >> /etc/mdadm/mdadm.conf
cat /etc/mdadm/mdadm.conf
DEVICE /dev/sd[a-f]1
ARRAY /dev/.tmp.md1 level=raid5 num-devices=4 UUID=0e741d8e:f05f0ea0:bb85ef38:5a659a3a
devices=/dev/sde1,/dev/sdd1,/dev/sdb1
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=090c2b51:f8408124:0044a52f:c59629ad
devices=/dev/sdf1,/dev/sda1
Note for device md1, /dev/sdc1 is not listed. For some reason mdadm
seems not to be seeing /dev/sdc1 even though the kernel sees it. The
system was rebooted after the partitions /dev/sd[bcde]1 were defined.
The drives are on two controllers, a-d are on an onboard sil and e-f
are on a 3com pci card.
Has anyone seen anything like this? How can it be fixed? Thanks.
Don
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