[K12OSN] Re: why RAID?

[Frank Samuelson]

>>why is it so important to get RAID set up?  Why not just
>>have a cron job that makes a copy of /home or any other
>>important directories?
> 
 >  My preference is RAID5 when possible because it gains the
 > best
 > of both worlds, but unfortunately you pay more for the controllers
 > that
 > handle it.  If you are on a budget crunch RAID0+1 in my opinion is the
 > next best option.

You can also run RAID 5 using software present in the
Linux kernel (as well as RAID 0 and 1), requiring no extra
controller$.  Software RAID is trickier than hardware (no-brainer)
RAID and requires more CPU cycles,
but it's equally fast and reliable, and it's cheap.

> 
> RAID levels 1 and 5 provide a sufficient redundancy that you
> can lose a disk without losing data. There are, of course,
> other tradeoffs; the redundancy comes at the price of additional
> disks and a performance impact on writes. There is also a gain in
> read performance.
> 

Generally, speeds aren't impacted terribly because writes are done
in parallel.