Monday, April 15, 2013

Linux System Admin Interview Questions and Answers part 5

How to find out Hardware Raid levels using command on Linux machine, with out rebooting the server.

Issue: My Linux Machine Hard disks were configured with Hard ware RAID level, but i want to know which RAID was configured on this machine?? 

if the machine was configured with s/w RAID , we have a command to check. /proc/mdstat. It will give us the Software Raid level information. we know that hard ware RAID is configured at BIOS level, so we can not see that one, with out rebooting the server.


# cat /proc/driver/cciss/cciss0

cciss0: HP Smart Array E200i Controller
Board ID: 0xxxxxxxxxx
Firmware Version: 1.84
IRQ: 82
Logical drives: 1
Current Q depth: 0
Current # commands on controller: 0
Max Q depth since init: 10
Max # commands on controller since init: 230
Max SG entries since init: 31
Sequential access devices: 0

cciss/c0d0:      299.96GB       RAID 1(1+0)

Here we can see that the machine is configured with RAID 1.  On HP server Smart Araay controller option will be available. With this controller we can create Hard ware RAID levels ,RAID 0 , RAID 1 or RAID 5, depending on requirement. 

Here we have two disks, with 300 GB each one, we crated raid 1, so we will get only ~300GB usable space.

ccisss/c0d0-- 1st Hard disk for HP servers.

Note: This command will work only for HP servers.

Hope it will helpful.