Rebuilding a Raid 1

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Rebuilding a Raid 1 – Managing your servers can streamline the performance of your team by allowing them to complete complex tasks faster. Plus, it can enable them to detect problems early on before they get out of hand and compromise your business. As a result, the risk of experiencing operational setbacks is drastically lower.

But the only way to make the most of your server management is to perform it correctly. And to help you do so, this article will share nine tips on improving your server management and fix some problem about linux, centos, dmraid, , .

I’m trying to rebuild a raid 1 (dmraid+isw) unsuccessfully. I replaced the failed disk with a new one and the BIOS added it automatically to the raid.
Running kernel 2.6.18-194.17.4.el5.

dmraid -r

/dev/sda: isw, "isw_babcjifefe", GROUP, ok, 1953525165 sectors, data@ 0
/dev/sdb: isw, "isw_babcjifefe", GROUP, ok, 1953525165 sectors, data@ 0

dmraid -s

*** Group superset isw_babcjifefe
--> Subset
name   : isw_babcjifefe_Raid0
size   : 1953519616
stride : 128
type   : mirror
status : nosync
subsets: 0
devs   : 2
spares : 0

When i try to start the raid i receive the next errors

dmraid -f isw -S -M /dev/sdb

ERROR: isw: SPARE disk must use all space on the disk

dmraid -tay

isw_babcjifefe_Raid0: 0 1953519616 mirror core 3 131072 sync block_on_error 2 /dev/sda 0 /dev/sdb 0

dmraid -ay

RAID set "isw_babcjifefe_Raid0" was not activated
ERROR: device "isw_babcjifefe_Raid0" could not be found

dmraid -f isw -S -M /dev/sdb

ERROR: isw: SPARE disk must use all space on the disk

dmraid -R isw_babcjifefe_Raid0 /dev/sdb

ERROR: disk /dev/sdb cannot be used to rebuilding

dmesg

device-mapper: table: 253:13: mirror: Device lookup failure
device-mapper: ioctl: error adding target to table
device-mapper: ioctl: device doesn't appear to be in the dev hash table.
device-mapper: table: 253:13: mirror: Device lookup failure
device-mapper: ioctl: error adding target to table
device-mapper: ioctl: device doesn't appear to be in the dev hash table.
device-mapper: table: 253:13: mirror: Device lookup failure
device-mapper: ioctl: error adding target to table
device-mapper: ioctl: device doesn't appear to be in the dev hash table.
device-mapper: ioctl: device doesn't appear to be in the dev hash table.
device-mapper: ioctl: device doesn't appear to be in the dev hash table.

Disks:

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

LVM:

PV /dev/sda5   VG storage   lvm2 [914.64 GB / 28.64 GB free]
Total: 1 [914.64 GB] / in use: 1 [914.64 GB] / in no VG: 0 [0   ]
Reading all physical volumes.  This may take a while...
Found volume group "storage" using metadata type lvm2
ACTIVE            '/dev/storage/home' [68.00 GB] inherit
ACTIVE            '/dev/storage/home2' [68.00 GB] inherit
ACTIVE            '/dev/storage/home3' [68.00 GB] inherit
ACTIVE            '/dev/storage/home4' [68.00 GB] inherit
ACTIVE            '/dev/storage/home5' [68.00 GB] inherit
ACTIVE            '/dev/storage/var' [15.00 GB] inherit
ACTIVE            '/dev/storage/mysql' [20.00 GB] inherit
ACTIVE            '/dev/storage/pgsql' [7.00 GB] inherit
ACTIVE            '/dev/storage/exim' [12.00 GB] inherit
ACTIVE            '/dev/storage/apache' [25.00 GB] inherit
ACTIVE            '/dev/storage/tmp' [2.00 GB] inherit
ACTIVE            '/dev/storage/backup' [450.00 GB] inherit
ACTIVE            '/dev/storage/log' [15.00 GB] inherit

Solution :

I am going to agree with Andrew.

Hopefully you can do a mount -o ro /dev/sd

Then, copy the data off of that drive and start over using mdadm and full, reliable, easy to use, fast software raid.

Good luck.

I’m not sure dmraid supports rebuilding a fakeraid (like isw). I would advise scraping the isw and build pure software raid with mdadm.

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