There is some confusion in the market place as to what raid 0+1 and raid 1+0 
are - in fact most times they are the same.

I think the confusion stems from you looking at it either from the os point of 
view or from the hardware side of things.

Many h/w vendors (like dell) approach it from the hardware so raid 10 is a 
mirror in a stripe (so from the os it is a stripe which is mirrored hence the 
0+1) - so from the os you have x stripes over x disks and each stripe/disk is 
then mirrored - this gives the performance of raid 0 but with the tolerance of 
raid 1. A raid0+1 from the hardware point of view would be stripe sets in a 
mirror.

I am not too sure on the difference in performance (there are slight 
differences in the tolerance in that they fail with differing drive losses) but 
I think when software (and some h/w) people talk about raid 10 or raid 1+0 or 
raid 0+1 etc they do in fact mean the same thing i.e raid 10 where each stripe 
consist of two mirrored disks.

Having said all that, Doug at EasyCo 's  new technology is the way to go !!


Symeon



-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of phil walker
Sent: 24 October 2007 21:36
To: [email protected]
Subject: [U2] Raid 0+1 versus Raid 10 1+0

Hi All,

I have just read a slide from the U2 University sessions whereby it states...

RAID 0+1 is absolutely the fastest implementation possible for disk drives

t>Internal and External Disk Drives -Raid 0+1, striping and mirroring
tWhen a mirrored disk drive is not committed to a WRITE, it is available for 
a READ
tAdditional throughput from RAID 0+1 is about 40%
tParity WRITEs never are in contention with the production disk drives. RAID 
5 will have a parity WRITE be in conflict with the Production Disk Drives
tHW level RAID implementation is far better than SW striping and HW mirroring
tStripe size was 128K. Any larger, and a file can be on a singledisk drive.

Can anyone tell me how it compares performance wise through theory or 
experience to RAID 10 which as a configuration is more fault tolerant and 
easier to rebuild?

Cheers,

Phil.
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