Re: HDD vs. RAID (was Re: Lilo Q)
On Sun, Jun 09, 2002 at 09:35:05AM -0400, Ian D. Stewart wrote:
> As the size of IDE hard drives increase, what are the
> advantages/disadvantages of using a single large hard drive as opposed
> to a RAID stack
Well, that depends on what flavor of RAID you're talking about...
In general:
RAID 0: Capacity = sum of all disks, improved performance, reduced
reliability (if one drive fails, everything goes with it)
RAID 1: Capacity = smallest disk, read performance could improve but
is usually not affected, write performance tends to be slower, best
reliability (as long as one disk survives, your data is OK)
RAID 5: Capacity = smallest disk * (number of disks - 1), improved
perfomance, data can survive failure of one disk, but all is lost if
a second disk fails before the contents of the first are regenerated
RAID 0+1: Capacity = smallest disk * (number of disks / 2), good
performance, good reliability
> (say, 80 GB hard drive vs. raid tower w/ 4 20 GB hard
> drives) ?
If you're getting 80G from 4*20G drive, that must be a RAID 0, so
the RAID would give you a nice boost to data transfer rates, but
you'd better keep a current backup because if any one of those 4
drives goes bad, you'll lose all your data. (OTOH, add a fifth 20G
drive, make it a RAID 5, and you'll have a winner.)
Side note: Comments on performance assume that each drive is on a
separate IDE channel all by itself. If your 4 20G drives are hda,
hdb, hdc, and hdd, you're going to take a major performance hit.
Unlike SCSI, IDE can't run two drives efficiently on the same
channel.
--
When we reduce our own liberties to stop terrorism, the terrorists
have already won. - reverius
Innocence is no protection when governments go bad. - Tom Swiss
--
To UNSUBSCRIBE, email to debian-user-request@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
Reply to: