Re: filmscanners: Best solution for HD and images

[Jim Snyder <jimsnyder@insight.rr.com>]

on 11/11/01 1:53 PM, LAURIE SOLOMON at LAURIE@ADVANCENET.NET wrote:

> Preben,
> Since you seem to be knowledgeable about IDE RAID matters, I wish to make
> use of your knowledge as a resource even if it is OT for this list.  I
> recently bought an ABIT motherboard with RAID.  The manual is not very clear
> as tot he difference between RAID 0 (striping) and what it does versus JBOD
> (spanning).  I understand what RAID 1 (mirroring) is and how it works; but I
> really do not understand how RAID 0 works or what parallel operation of the
> two drives on the channel means and entails.
> 
> While it may be different for third party RAID controllers, the manual for
> the RAID controller on the ABIT KG7-RAID motherboard says that you need 4
> drives to use RAID 0+1 and that the second pair duplicate the first pair.
> This appears to contradict your point concerning "You  "pay" the equivalent
> of one drive i.e.. - in this case - 100 GB for the security of your data,
> but you end up with a 300 GB drive array."  If I ma reading the manual
> correctly, at least on the ABIT RAID, you would have 200GB of original data
> storage and 200GB duplicate mirror backup protection under the RAID 0+1
> setup - especially if you follow their advice of using same size, make, and
> model of hard drive in the array.  Could you comment on this in a way so as
> to add some clarification for a novice to RAID arrays.
> 
You have it exactly correct, Laurie. The RAID 0 is taking half the data and
pushing it to one hard drive, and the other half to the second, giving you a
slight edge in speed since the bus to each hard drive can be loaded while
the other hard drive is munching on the data it just received. RAID 0+1 does
exactly as you have described, striping data, but also mirroring it on a
second set of drives. To use RAID effectively, both (or all) drives should
ideally be of the same make and model, as even caching algorythims play a
part. You can make RAID work with less than equal matches, but at a lost of
capacity and speed, usually more than negating the advantage of RAID.

Jim Snyder