RAID 5 - How do I detect if a disk has failed, and which one?

Question

I bought an IBM eSeries with 5 disks of 36GB each.

I would like to make a RAID5 out of it.

I want to know how can I detect if a disk has failed or needs to be changed. If one fails, does the system will continue to operate anyway? And how can I know which disk has failed? How does the system tell me which disk to change? And how can I monitor the disk rebuild and how can I know when the rebuild is done?

I have so much questions about this RAID thing, sorry :)

p.s.: Ill use Debian 6

Answer 1

If one fails, does the system will continue to operate anyway?

Yes, that's what RAID5 is about: surviving the failure of one physical disk.

And how can I know which disk has failed? How does the system tell me which disk to change?

The RAID controller will recognize failed disk, obviously. Your operating system needs to have a corresponding software installed to interact with the controller, retrieve its status and send a notification if it's having problems.

Unfortunately, IBM provides such software (ServeRAID Manager) only for Red Hat and SLES:

http://www.ibmquicklinks.com/downloads/downloads/ibm/serveraid/8.20b/40k8640.txt

Answer 2

Are you talking about Linux md software RAID ? If it's hardware raid, you will need to look at manufacturers manual.

If linux md raid then :

I would like to make a RAID5 out of it

mdadm --create /dev/md1 --level=5 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1 

Where /dev/sdxx are your hard drive partitions. You need to list all five.

I want to know how can I detect if a disk has failed or needs to be changed

You will get an error message in syslog / messages log. To manually check the status

mdadm --detail /dev/md1

The system will be up and running that's the whole point of RAID.

I have so much questions about this RAID thing, sorry :)

More here

Read the manuals and try to research on your own first before posting questions here.