disk failure with swap RAID-0

[Joel Jaeggli]

On Mon, 9 Jan 2006, Doncho N. Gunchev wrote:

> On Friday 06 January 2006 16:38, Jack Howarth wrote:
>>     In installing Fedora Core 4 on a new workstation here, the owner of
>> the machine decided he wanted RAID-1 on all of his partitions except for
>> the swap which he set up as RAID-0 across the two drives. I pointed out
>> that this would make the machine fault intolerant since it will likely
>> crash if half the swap disappears with a drive failure. He doesn't mind
>> that but I am still concerned about the recovery from such a drive failure.
>> Does anyone know what sequence you would have to go through to recover
>
> Replace the bad disk and restore the RAID-1 arrays (mdadm). To boot from
> the second drive you have to do some map-root-setup tricks with grub (search
> grub raid1 in google for more info).
>
>> in such a situation? Specifically is there a way to boot linux with the
>> swap disabled for that particular boot? Otherwise I would imagine I'd have
>> to use a linux rescue cd to edit the fstab on the remaining drive and
>> change the swap back to a single partition on a single drive. Thanks in
>> advance for any clarifications on this issue.
>>           Jack
>
> The machine will boot fine, just will not have swap at all. Why not use two
> swap partitions instead of one RAID-0? This way at least one of them will
> work (if one disk is gone).

If you just set the priority of the swap partitions to the same thing (1 
for example) the kernel will sanely divide swap usage between them. 
swapping to a raid 0 is just making the machine do unecessary work.

>

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Joel Jaeggli  	       Unix Consulting 	       joelja at darkwing.uoregon.edu
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