[ale] motherboard RAID versus software RAID

[Jim Popovitch]

John Wells wrote:
> 
> I'm afraid an extra purchase is out of the question currently, I'll take
> it from your comments that if choosing between Linux's software RAID and
> the Asus RAID, you'd choose the former.
> 
> What sort of problems did you have, if you don't mind me asking? How did
> they manifest themselves?

I have never had any significant software raid1 problems, the most 
bothersome was a partition problem that caused me to have to drop the 
one raid partition (which happened to be /www on a busy server) and 
re-sync the raid array on a newer partition.  No data was ever lost.

Wrt the ASUS/Promise controllers, my problems centered around Linux 
driver changes/issues.  This was a few years back, so Geoffery's advice 
about mixing past w/ present could hold true to my experience.  Back 
then I remember completely rebuilding RAID arrays (and restoring data 
from backup) because of some significant changes in Promise support.

If you are doing RAID1, the nice thing about software raid is that even 
if the raid drivers fail to load (i.e. /etc/raidtab gets fatfingered), 
you can still load the partition as /dev/hdaX instead of /dev/mdX.  With 
a hardware raid controller that probably isn't possible.

The other concern you should pay attention to is that a hardware raid 
controller will generally handle writing large files (or large number of 
files) better than software raid.

-Jim P.