[CentOS] Anaconda doesn't support raid10

Ruslan Sivak rsivak at istandfor.com
Tue May 8 17:09:20 UTC 2007


Andreas Micklei wrote:
> Am Montag, 7. Mai 2007 schrieb Ruslan Sivak:
>   
>> I've just installed the system as follows
>>
>> Raid1 for /boot with 2 spares (200mb)
>> raid0 for swap  (1GB)
>> raid6 for / (10GB)
>>     
>
> NEVER EVER use raid0 for swap if you want reliability. If one drive fails the 
> virtual memory gets corrupted and the machine will crash horribly (tm). 
> Besides creating sepearte swap partitions on different physical discs will 
> give you the same kind of performance, so using striping on a swap parition 
> is kind useless for gaining performance.
>
> I suggest using raid-1 or raid-6 for swap, so the machine can stay up if one 
> drive fails.
>
>   
Interesting thing... I build the following set up:

/boot on raid1
swap on raid0
/ on raid6
/data on 2 lvm raid1's.

I shut down and plucked out one of the drives (3rd one I believe).  
Booted back up, everything was fine.  Even swap (I think).  I, rebooted, 
put in the old drive, hot added the partitions and everything rebuilt 
beautifully.  (again not sure about swap).

I decided to run one more test.  I plucked out the first (boot) drive.  
Upon reboot, I got greeted by GRUB all over the screen.  Upon booting 
into rescue mode, it couldn't find any partitions.  I was able to mount 
boot, and it let me recreate the raid1 partitions, but no luck with 
raid6.  This is the second time that this has happened.  Am I doing' 
something wrong?  Seems when I pluck out the first drive, the drive 
letters shift (since sda is missing, sdb becomes sda, sdc becomes sdb 
and sdd becomes sdc). 

What's the proper repair method for a raid6 in this case?  Or should I 
just avoid raid6, and put / on 2 an LVM of 2 raid1's?  Any way to set up 
interleaving  (although testing raid1 vs raid10 with hdparm -t gives 
only marginal performance improvement).

Russ





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