Failed disk in Raid

Michael J. Pawlowsky mikep at mi-consultants.com
Mon Dec 27 18:44:25 UTC 2004


Ed Wilts wrote:

>>Well it looks like last night it paid off.
>>I received a disk failed event.
>>My primary / partition has a block that is not writeable on /dev/hda
>>
>>But since this is my home machine, and my $ are a bit more precious to me, 
>>I was thinking of removing all the partitions from the raid and trying 
>>to fix it using chkdisk and then adding it back into the raid.
>>
>>What do you think?
>>    
>>
>
>Bad idea.  Assuming you meant mirroring and not striping, you do have
>your partitioned data on a mirror member but remember that the MBR is
>not automatically mirrored.  You could try running the badblock utility
>on the failing drive and try to map the bad block out, but in my
>experience (going back about 25 years), once a drive starts to fail, it
>is on its way down and you get a another day or month out of it, but you
>will lose the drive - it's just a matter of when.
>
>Bottom line:
>1.  Check to make sure you're mirrored and not striped.
>2.  Replace the drive.
>
>  
>

Yes it is RAID 1. Sorry for the mix up.
And I already took your advice and went out and bought another drive.

I do realize that the MBR is not mirrored. But I did a grub install on 
both disks as (hd0,0)
So basically I just moved the good disk to become /dev/hda instead of  
/dev/hdc put the new disk in and it boots up.
If it was not the /dev/hda disk that went it would have even been easier.

With SCSI disks it's even better, I just remove the disk completely and 
it boots back up.
On my customers machine we have a spare disk in it. So when one goes it 
already rebuilds the mirror on the spare disk.
Of course this stuff has been around for years. And I've put harware 
RAID 5 systems in place over 15 years ago. And it was a thrill to be 
able to hot remove a disk from the array and watch everything go on.

So although, this is all old stuff... I think it is great to be able to 
easily afford this technology for a home system now.
At the time the idea of having raid for your home PC was for those with 
$$$ to burn only.

Thanks for the feedback. I knew that's what I should do, but was 
thinking foolishly to save a few dollars after the X-mas $$$ crunch.

Mike





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