RAID5 for Linux

[richb at pioneer.ci.net (Rich Braun)]

Bob Keyes wrote:
> Now that the reason for the number of drives was explained to me, it makes
> sense. I may be able to use software RAID on a low-end system after all.
> But for some reason, SCSI doesn't have a lot of respect around this
> office.

Just to be clear:  I am not recommending that you consider SCSI; I am
recommending taking a look at (parallel) IDE vs. serial ATA, and at software
vs. hardware RAID.

The price premium for SCSI is rarely worth it, only in high-end systems built
with it.  Or in obsolescent systems that you inherited from someone else. 
(But don't use hard drives older than about 5 years, when manufacturers
finally figured out how to make them truly durable.)

You can easily build a 4-drive IDE configuration with software RAID1, 600 gigs
usable, by getting the cheapest 300Gb drives on the market.  A RAID5
configuration would give you 900 gigs using the same 4 300Gb drives.

I don't know too many environments where you really need that much data.  One
other comment I should make about a typical corporate installation:  high
capacity filesystems make people lazy about cleaning out old data.  Most
companies should throw out 99% of the junk they've accumulated.  But they
don't bother because hard drives are cheap.

But if folks don't clean out the crap, there is a cost to consider:  backups. 
Tape drives are nowhere near as cheap as disks, and handling large backup
libraries is a time-consuming administrative hassle.

-rich