your advice on vinum, RAIDs

Chuck Swiger cswiger at mac.com
Thu Dec 29 06:31:14 PST 2005


Joe Auty wrote:
> I've been considering buying another hard drive for my FreeBSD  machine, 
> and building a RAID with my current hard drive so that both  drives are 
> treated as one.

This is known as RAID-1 mirroring.

> Do any of you have experience in this area? Is this advisable? 

Yes and yes.  :-)

> I'm assuming I'd be looking at creating a RAID-5?

Not with only two drives.
RAID-5 needs at least 3, and is wasteful unless you have 4-5.

> Can this be done without reformatting my current drive?

You can set up mirroring without reformatting, but be sure you have good backups 
of your data regardless.

> Does this setup work well?  Do you have any general advice for me? I need to
> know if there is risk  involved here.

When choosing RAID levels, you are making a tradeoff between performance, 
reliability, and cost:

If you prefer...             ...consider using:
-----------------------------------------------
performance, reliability:    RAID-1 mirroring
performance, cost:           RAID-0 striping
reliability, performance:    RAID-1 mirroring (+ hot spare, if possible)
reliability, cost:           RAID-5 (+ hot spare)
cost, reliability:           RAID-5
cost, performance:           RAID-0 striping

If you've got enough drives, using RAID-10 or RAID-50 will also improve 
performance compared to stock RAID-1 or RAID-5 modes.

-- 
-Chuck


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