[CentOS] DegradedArray message
Digimer
lists at alteeve.ca
Wed Dec 3 01:28:24 UTC 2014
On 02/12/14 08:14 PM, David McGuffey wrote:
> Received the following message in mail to root:
>
> Message 257:
> From root at desk4.localdomain Tue Oct 28 07:25:37 2014
> Return-Path: <root at desk4.localdomain>
> X-Original-To: root
> Delivered-To: root at desk4.localdomain
> From: mdadm monitoring <root at desk4.localdomain>
> To: root at desk4.localdomain
> Subject: DegradedArray event on /dev/md0:desk4
> Date: Tue, 28 Oct 2014 07:25:27 -0400 (EDT)
> Status: RO
>
> This is an automatically generated mail message from mdadm
> running on desk4
>
> A DegradedArray event had been detected on md device /dev/md0.
>
> Faithfully yours, etc.
>
> P.S. The /proc/mdstat file currently contains the following:
>
> Personalities : [raid1]
> md0 : active raid1 dm-2[1]
> 243682172 blocks super 1.1 [2/1] [_U]
> bitmap: 2/2 pages [8KB], 65536KB chunk
>
> md1 : active raid1 dm-3[0] dm-0[1]
> 1953510268 blocks super 1.1 [2/2] [UU]
> bitmap: 3/15 pages [12KB], 65536KB chunk
>
> unused devices: <none>
>
> & q
> Held 314 messages in /var/spool/mail/root
> You have mail in /var/spool/mail/root
>
> Ran a madam query against both raid partitions:
>
> [root at desk4 ~]# mdadm --query --detail /dev/md0
> /dev/md0:
> Version : 1.1
> Creation Time : Thu Nov 15 19:24:17 2012
> Raid Level : raid1
> Array Size : 243682172 (232.39 GiB 249.53 GB)
> Used Dev Size : 243682172 (232.39 GiB 249.53 GB)
> Raid Devices : 2
> Total Devices : 1
> Persistence : Superblock is persistent
>
> Intent Bitmap : Internal
>
> Update Time : Tue Dec 2 20:02:55 2014
> State : active, degraded
> Active Devices : 1
> Working Devices : 1
> Failed Devices : 0
> Spare Devices : 0
>
> Name : desk4.localdomain:0
> UUID : 29f70093:ae78cf9f:0ab7c1cd:e380f50b
> Events : 266241
>
> Number Major Minor RaidDevice State
> 0 0 0 0 removed
> 1 253 3 1 active sync /dev/dm-3
>
> [root at desk4 ~]# [root at desk4 ~]# mdadm --query --detail /dev/md1
> /dev/md1:
> Version : 1.1
> Creation Time : Thu Nov 15 19:24:19 2012
> Raid Level : raid1
> Array Size : 1953510268 (1863.01 GiB 2000.39 GB)
> Used Dev Size : 1953510268 (1863.01 GiB 2000.39 GB)
> Raid Devices : 2
> Total Devices : 2
> Persistence : Superblock is persistent
>
> Intent Bitmap : Internal
>
> Update Time : Tue Dec 2 20:06:21 2014
> State : active
> Active Devices : 2
> Working Devices : 2
> Failed Devices : 0
> Spare Devices : 0
>
> Name : desk4.localdomain:1
> UUID : 1bef270d:36301a24:7b93c7a9:a2a95879
> Events : 108306
>
> Number Major Minor RaidDevice State
> 0 253 0 0 active sync /dev/dm-0
> 1 253 1 1 active sync /dev/dm-1
> [root at desk4 ~]#
>
> Appears to me that device 0 (/dev/dm-2) on md0 has been removed because
> of problems.
>
> This is my first encounter with a raid failure. I suspect I should
> replace disk 0 and let the raid rebuild itself.
>
> Seeking guidance and a good source for the procedures.
>
> Dave M
In short, buy a replacement disk equal or greater size, create matching
partitions and then use mdadm to add the replacement partition (of
appropriate size) back into the array.
An example command to add a replacement partition would be:
mdadm --manage /dev/md0 --add /dev/sda1
I strongly recommend creating a virtual machine with a pair of virtual
disks and simulating the replacement of the drive before trying it out
on your real system. In any case, be sure to have good backups
(immediately).
--
Digimer
Papers and Projects: https://alteeve.ca/w/
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