[CentOS] RAID6 in production?

Aleksandar Milivojevic alex at milivojevic.org
Thu Oct 20 14:43:29 UTC 2005

Quoting Joshua Baker-LePain <jlb17 at duke.edu>:

> Needless to say it's not giving me that warm fuzzy feeling.  The one 
> caveat is that not all the members of my array were the same size -- 
> one disk is 180GB while all the rest are 160GB.  I'm going to test 
> overnight with identically sized RAID members, but I also wanted to 
> see if anyone else is using RAID6.

I was testing RAID-5 with identical disk drives.  Got the same thing.  If I
attempt to access it while it rebuilds, sooner or later I get errors.  If I
reboot while it rebuilds, it doesn't start it after the reboot (forgot the
actuall error message).  I needed to manually kick it again using mdadm to
force-start it.  If it was root file system, the machine would probably 
fail to
boot completely.  You might want to stick to your 3ware for now.

BTW, any particular reason not to use hardware RAID on 3ware?

I was testing software RAID-5 only because I had an old and slow Adaptec 2400
RAID controller.  Software RAID-5 (on an older 1.8GHz CPU) across 4 drives
connected to it in JBOD config was about 60% faster than hardware RAID-5.  But
as I said, because of the described problems, I decided to stick with hardware
RAID.  Adaptec 2400 is a slow card, but it allowed me to use the array 
while it
was rebuilding (and I could safely reboot machine while it was 
rebuilding too).

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