Re: Upgrading a software RAID

["Keld Jørn Simonsen" <keld@dkuug.dk>]

On Thu, May 28, 2009 at 10:32:53AM -0400, Maxime Boissonneault wrote:
>
> Robin Hill a écrit :
>> On Mon May 25, 2009 at 01:05:15PM -0400, Maxime Boissonneault wrote:
>>
>>   
>>> Hello,
>>> I am using Ubuntu Hardy with 3x500GB drives and the following RAID
>>> configuration :
>>>
>>> /boot is on a 100MB RAID1
>>> / is on a 30GB RAID0
>>> /home is on a 906GB RAID5
>>>
>>>     
>> Ouch - why RAID0 for /?  If you lose a single drive then all the
>> configuration, etc. is down the drain.  I'd suggest rethinking this
>> while you're going through the rebuild process anyway.
>>
>>   
> That is why I do backups of / on /home regularily. I first did a RAID0  
> for performance. I did some testing on performance of RAID0,1,5 and  
> RAID1 was pretty lousy (I put the results of my tests here :  
> http://cqed.physique.usherbrooke.ca/~mboisson/htpc.php?sec=raid_test )
> I guess I should have used a RAID5, but RAID1 seems like a terrible idea  
> considering the really bad performances.

Hmm, why not use raid10,f2 for the / system?
Then you will get almost raid0 read performance, while write performance
is about half of raid0.

A setup is described in
http://linux-raid.osdl.org/index.php/Preventing_against_a_failing_disk

You can do the / system with raid10,f2 with just 2 disks.

Best regards
keld
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