Does this server have RAID configured correctly?

Nunawading · 10-04-2009, 06:44 AM

Hi All,

Hopefully this is a quick question. We have a system, but we're not sure if there's RAID installed or not. It looks like it's using some form of Fake Raid. My suspicion is that the fakeraid is configured correctly, but the volume groups are actually created directly on the physical disk (sda). Is that even possible? Or is the mirror set up correctly?

I think the pertinent information is below, but I can provide as much diagnostic information as required. Let me know if there's anything else that will help?

Thanks in advance for your help.

Code:

[root@mx ~]# fdisk -l

Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   83  Linux
/dev/sda2              14       30377   243898830   8e  Linux LVM

Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1          13      104391   83  Linux
/dev/sdb2              14       30377   243898830   8e  Linux LVM

[root@mx ~]# ls /dev/mapper/
control  VolGroup00-LogVol00  VolGroup00-LogVol01

[root@mx ~]# dmraid -r
/dev/sda: ddf1, ".ddf1_disks", GROUP, ok, 488017920 sectors, data@ 0

[root@mx ~]# dmraid -b
/dev/sda:    488397168 total, "6RYAEL4Z"
/dev/sdb:    488397168 total, "6RYADTQ1"

[root@mx ~]# dmraid -s -c -c -c
ddf1_RM:488017920:128:mirror:ok:0:2:0
/dev/sda:ddf1:ddf1_RM:mirror:ok:488017920:0
/dev/sdb:ddf1:ddf1_RM:mirror:ok:488017920:0

[root@mx ~]# pvdisplay 
  Found duplicate PV aLNQfrXT3tOfRa1ArmNvD7T6RK9qH0LQ: using /dev/sdb2 not /dev/sda2
  --- Physical volume ---
  PV Name               /dev/sdb2
  VG Name               VolGroup00
  PV Size               232.60 GB / not usable 6.45 MB
  Allocatable           yes (but full)
  PE Size (KByte)       32768
  Total PE              7443
  Free PE               0
  Allocated PE          7443
  PV UUID               aLNQfr-XT3t-OfRa-1Arm-NvD7-T6RK-9qH0LQ

pingu · 10-05-2009, 02:17 AM

You are using LVM here, not RAID.
Which you should use depends on what you want to achieve - handle diskspace efficiently or fault-tolerance?
My guess, since this is a server, is that you want fault tolerance so you should go for RAID.
Taka a look at mdadm, an application to handle software raid. You'll find a manual here: http://www.linuxmanpages.com/man8/mdadm.8.php

Nunawading · 10-05-2009, 02:24 AM

Thanks. Is it not possible to use LVM on top of fakeRAID?