topic disk replacement in Operating System - Linux

disk replacement

Wilfred Chau_1 — Thu, 22 Jun 2006 13:16:22 GMT

Hi,
What is the procedure for replacing a bad disk on a Red Hat AS system?

Thanks.

Re: disk replacement

Ivan Ferreira — Thu, 22 Jun 2006 13:52:09 GMT

Your question really depends of several factors:

Is this disk mirrored by hardware?
Is this disk mirrored by software?
Is this disk part of a LVM configuration?
Is this disk holding part of the operating system?

Re: disk replacement

Wilfred Chau_1 — Thu, 22 Jun 2006 14:13:53 GMT

This is what I have. Disk at scsi id 1 died. Is that sdb or sda?

Filesystem Size Used Avail Use% Mounted on
/dev/sdb1 135G 16G 112G 13% /
/dev/sda1 99M 9.9M 84M 11% /boot
none 2.0G 0 2.0G 0% /dev/shm

I am still checking to see if the bad disk is mirrored or not.

Re: disk replacement

Ivan Ferreira — Thu, 22 Jun 2006 14:37:24 GMT

From your command output is very extrange, if you have only two disks, probably you don't have any mirror, as you can see sda and sdb in the ouput, but sda is used only for /boot, where is the rest of sda, maybe swap?

The sdb disk is the root itself, but if the disk failed, how come you can still access to the operating system?

So, I must ask, why do you think that you disk failed?

To try to identify your disk mapping, use the dd command to generate high I/O to your disk, and check the disk activity LED, in this way you may identify which disk is sda and sdb:

dd if=/dev/sda of=/dev/null bs=8k

Check the LEDs

dd if=/dev/sdb of=/dev/null bs=8k

Check the LEDs

By identifying your failed disk, more help can be given.

Re: disk replacement

sathish kannan — Fri, 23 Jun 2006 09:36:18 GMT

Hi Chau,

Looks like you have disks sda and sdb. sda being your root disk, I hope sdb is second disk. Does your disk has any hardware mirroring? better to check your "dmesg", "/var/log/messgaes" file for error.

In short and sweet, if your disk is failed on Linux and if no mirror copies available you need to restore data and recreate your partintion. Hopefully, you have your partiotion information??

Regards
Sathsih

Re: disk replacement

Alan_152 — Fri, 23 Jun 2006 09:37:47 GMT

do a backup of both sda and sdb to either a tape device, DVD-R, or another disk. You can use dd or tar for this operation.

Replace the disk, and boot with an Ubuntu or Knoppix live CD. Recover your data from the dd or tar file from the backup.