SUMMARY: Volume Manager and T3

From: Callum Hughes <>
Date: Tue May 07 2002 - 05:49:43 EDT
Hi everyone!

First of all, many thanks to the following people for their informative and
useful responses:

Rob Forsey
Darren Moulding
Tony Walsh
Eric Shafto
Wayne McCormick
Darren Dunham
Deborah Crocker
Charlie Giannetto
Christopher Ciborowski
Joe Serra
Doug Otto
Mailing List (???)
Vipin Sharma

I'll briefly summarize the two main points people made:

1) Volume Manager is only presented with LUN's and as a result, is not able
to see an individual disk failure in a RAID 5 configuration. My concern
however stemmed from the results of tests we performed on a RAID 0
configuration whereby the entire LUN did fail (as you would expect) when a
single disk failed. However, with the RAID 5 configuration, the T3 brings in
the hot spare and begins rebuilding the LUN automatically and completely
transparently as far as VM is concerned. The only concern voiced was that
there may be an impact on performance. 

2) The T3's can be configured as "partnered pairs" which enables you to use
the VM DMP feature. I don't know enough about T3's but this sounds very much
like multi-pathing on Clariion arrays. I might be completely wrong about
that one though so I'd recommend checking up on that if not sure! 

Just to see this all for myself, I pulled a disk from one of the T3's in a
RAID 5 configuration and yes, VM chugged away merrily whilst the T3 brought
in the hot spare and started building on that. VM was indeed completely
oblivious to the "failure" and no problems encountered. 

So I was quite a happy bunny really!


Callum A. Hughes
Unix Systems Engineer

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Received on Tue May 7 05:57:23 2002

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