Raid Deffinitions

Joel Jaeggli joelja at darkwing.uoregon.edu
Thu Oct 9 18:08:51 EDT 2003


On Thu, 9 Oct 2003, Andrew Latham wrote:

> thanks.
> 
> I know that all the different raid levels are here for a reason and raid5 is
> great but what are the benefits of the rest?

0 is fast (interleaved chunks) but provides no redundancy.

1 is a a 1 + 1 mirror... can be faster on reads but is generally slower on 
writes depending on your controller/implementation...

0 + 1 or 1 + 0  striped mirror or mirrored stripe. less space efficient 
than raid 5 but faster in general. can survive multiple disk failures so 
long as both disks containing the same information don't fail at once.
 
> --- Mark Hahn <hahn at physics.mcmaster.ca> wrote:
> > > Discussing a client setup the other day a cohort and I came to a different
> > > opinion on what each raid level does. Is there a guide/standard to define
> > how
> > > it should work. Also do any vendors stray from the beaten path and add
> > there
> > > own levels?
> > 
> > sure they do.  IMO the only important levels are:
> > 
> > raid0 - striping
> > raid1 - mirroring
> > raid5 - rotating parity-based array
> > 
> > vendors who make a big deal of obvious extensions like raid 10 
> > (mirrored stripes or vice versa) are immediately hung up on by me...
> > 
> 
> 
> =====
> Andrew Latham
> 
> Penguin loving, moralist agnostic.
> 
> LathamA.com - (lay-th-ham-eh)
> lathama at lathama.com - lathama at yahoo.com
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Joel Jaeggli  	       Unix Consulting 	       joelja at darkwing.uoregon.edu    
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