View Full Version : [ubuntu] mdadm RAID 5 - is there something wrong here?

July 14th, 2008, 05:38 AM
So I have a server with 5 1tb hard drives that have been working in a RAID 5 configuration for about 8 months now. Everything is working fine, I am just wanting to add three more hard drives to the array (grow it). Well I went to check the status on the current RAID 5 before I get ready to add the other three hard drives to it and it looks like there are only 4 hard drives working for some reason. Here is details from mdadm:

harold@server:~$ sudo mdadm --detail /dev/md0
Version : 00.90.03
Creation Time : Mon Feb 11 16:48:31 2008
Raid Level : raid5
Array Size : 3907039744 (3726.04 GiB 4000.81 GB)
Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
Raid Devices : 5
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent

Update Time : Sun Jul 13 23:12:12 2008
State : clean, degraded
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0

Layout : left-symmetric
Chunk Size : 64K

UUID : 72fa18f5:bf5d1a62:31a05266:02bffc2c
Events : 0.54

Number Major Minor RaidDevice State
0 8 113 0 active sync /dev/sdh1
1 0 0 1 removed
2 8 33 2 active sync /dev/sdc1
3 8 49 3 active sync /dev/sdd1
4 8 65 4 active sync /dev/sde1

I dont know why I am getting this error:

1 0 0 1 removed

If I go into the partition editor I can see that I have all eight hard drives hooked up to the computer and running, but I just don't understand this. I am not the greatest with linux but am getting be decent, so take it easy on me! Thanks!


July 14th, 2008, 06:05 PM
Anybody have any ideas? I really am not the greatest with linux but would like to make sure that it is working correctly.

July 19th, 2008, 02:26 PM
Looking at the output of: sudo mdadm --detail /dev/md0 you will see the lines:

Raid Devices : 5
Total Devices : 4

This means that your RAID device is a RAID 5 type.
Unfortunately one of your device seems to be missing OR has failed.

Since your RAID 5 device is missing one (1) component,
your data is still intact but the RAID device cannot afford another
failing component.

You must add another/separate Linux RAID partition immediately...
by using the --manage /dev/md0 --add /dev/???

Don't forget to create a disk partition (must be on another disk)
of EXACTLY the same size (use blocks not megabytes/gigabytes) as
that of the other components of your RAID device.