Identifying The Failed Drive - Novell LINUX ENTERPRISE SERVER 10 - STORAGE ADMINISTRATION GUIDE FOR EVMS Administration Manual

can survive a single disk failure at a time. A RAID 4 can survive a single disk failure at a time if the
disk is not the parity disk.
Disks can fail for many reasons such as the following:
When a disk fails, the RAID removes the failed disk from membership in the RAID, and operates in
a degraded mode until the failed disk is replaced by a spare. Degraded mode is resolved for a single
disk failure in one of the following ways:

6.5.2 Identifying the Failed Drive

On failure, md automatically removes the failed drive as a component device in the RAID array. To
determine which device is a problem, use mdadm and look for the device that has been reported as
"removed".
1 Enter the following a a terminal console prompt
For example, an mdadm report for a RAID 1 device consisting of /dev/sda2 and /dev/sdb2
might look like this:
blue6:~ # mdadm -D /dev/md1
/dev/md1:
Creation Time : Sun Jul
Raid Devices : 2
Total Devices : 1
Preferred Minor : 1
Active Devices : 1
Working Devices : 1
66 SLES 10 Storage Administration Guide for EVMS
Disk crash
Disk pulled from the system
Drive cable removed or loose
I/O errors
Spare Exists: If the RAID has been assigned a spare disk, the MD driver automatically
activates the spare disk as a member of the RAID, then the RAID begins synchronizing (RAID
1) or reconstructing (RAID 4 or 5) the missing data.
No Spare Exists: If the RAID does not have a spare disk, the RAID operates in degraded mode
until you configure and add a spare. When you add the spare, the MD driver detects the RAID's
degraded mode, automatically activates the spare as a member of the RAID, then begins
synchronizing (RAID 1) or reconstructing (RAID 4 or 5) the missing data.
mdadm -D /dev/md1
Replace /dev/md1 with the actual path for your RAID.
Version : 00.90.03
Raid Level : raid1
Array Size : 180201024 (171.85 GiB 184.53 GB)
Device Size : 180201024 (171.85 GiB 184.53 GB)
Persistence : Superblock is persistent
Update Time : Tue Aug 15 18:31:09 2006
State : clean, degraded
2 01:14:07 2006