How can I know what RAID configured on my machine

[Anh-Thu Tran]

I am not the one installed the box at the begining, how can I know what RAID configured on my machine? My box is IBM with Redhat ES3 on it. Is there an utility that I can run to check it when the machine running?

[Ivan Ferreira]

If you are using hardware RAID, you need to search in the IBM site a utility that configures the RAID, it will show the status also. Find it by your server model.

If you are using software RAID, just type:

cat /proc/mdstat

If you don't find the utility, you can calculate the RAID level, by knowing the total physical disks, and the available space for use at the OS level. You need at least 2 disks for a mirror and 3 for a RAID 5. Use fdisk -l to show the disk size:

RAID5: Usable size: N disks - 1 disk
RAID1: N disks / 2
RAID0: Sum of all disks
Spare: 1 disk unused.

[Anh-Thu Tran]

the /proc/mdstat shows:
# more mdstat
Personalities :
read_ahead not set
Event: 0
unused devices:

They told me that the machine has been configured with RAID 5, so I suppose to see Raid 5 in Personalities field. However, nothing shows here. I also could not find /etc/raidtab file. Besides that, I found
# mdadm --query /dev/md0
/dev/md0: is an md device which is not active
/dev/md0: is too small to be an md component.
root@fwcl7:/proc
# mdadm --detail /dev/md0
mdadm: md device /dev/md0 does not appear to be active.

I followed your advice to check the disk capacity (fdisk -l), and look like it is RAID 5 since we have 6 disks with 73G/disk and total shows 293.6 g ~ 6disks - 1disk for RAID 5 - 1 spare disk. I am confused now.

[Ivan Ferreira]

You are using a hardware raid, not a software raid. Only if you have software raid you will see the status in /proc/mdstat. And, as you have a hardware RAID, you need a tool from the IBM site to verify/configure the array.