[Gllug] Multiple Raid Levels On Sarge

[James Roberts]

Jim Bailey wrote:
>>> I supposed after all that what I am asking is can people see any gotchas
>>> with this I am unsure of the reliability of the two raid 5 partitions and
>>> or write performance.

>> I'd *really* want a hot spare on each array...
> Not practical this is backup storage will be monitoring the system for
> disk errors and can in an emergency float it off to the archive space on
> a Pillar NAS.

> This is about recycling old hardware and using new disks to get a better
> than before solution.

Fair enough. It's very inefficient disk wise compared with 5x500 in a 
RAID5 and a hot spare but you know that :)

I can find no data on-line on the likely performance of the i4 in this 
configuration and have no experience of the product. But I would not 
expect RAID50 write performance (with two on-board controllers) would be 
anything like as fast as RAID10 (this is certainly the case for all 
configs with the 3Wares we use).

Dunno if this would help (prob'bly not):

http://germany.3ware.com/products/pdf/Benchmark_7500-8_RAID-5.pdf#search=%22Megaraid%20i4%20performance%22

It's from 3Ware so may be biased (and is on Windows server) but does not 
show i4 write performance in RAID5 as being very good.

BSD had a few write issues too:

http://archives.neohapsis.com/archives/openbsd/2004-09/1332.html

but doesn't mean 'twas the card of course. Good luck.

J
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