Veritas-bu

[Veritas-bu] Scratch Pool Usage

2005-05-04 09:45:29
Subject: [Veritas-bu] Scratch Pool Usage
From: pkeating AT bank-banque-canada DOT ca (Paul Keating)
Date: Wed, 4 May 2005 09:45:29 -0400
I'd have to say it depends on the system, and what you get in testing.

I never implement something without testing the options first.

In my case, Exchange for example, has 4 Storage groups....totalling ~600
Gig.

SG1 and SG3 are on a single RAID5 array, and SG2 and SG4 are on another
RAID5 array.

Here's what I found in testing:

One SG to one drive:                                    ~20 Mbytes/sec
Two SG (from same RAID array) to one drive:     ~17-18 Mbytes/sec per SG

Once the other two SGs were added in, the performance dropped...likely
due to the network load.....the drives were no longer the bottleneck.
Running all 4 SGs at once to 4 drives, performance was down to about 13
Mbytes per sec.....
Running 4 SGs in 4 streams, mpx to 2 drives I was getting 16-17
Mbytes/sec per stream.

It would seem running to 4 drives was providing insufficient data to
each drive, so they weren't streaming....MPXing to 2 per drive actually
bumped performance UP!!!

Paul




> -----Original Message-----
> From: veritas-bu-admin AT mailman.eng.auburn DOT edu 
> [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of 
> Bobby Williams
> Sent: May 4, 2005 8:34 AM
> To: Larsen, Errin M HMMA/IT; veritas-bu AT mailman.eng.auburn DOT edu
> Subject: RE: [Veritas-bu] Scratch Pool Usage
> 
>  
> My opinion on this (and I have multiple systems over 500GB) 
> is to not do MPX on this Big system, but use the multiple 
> data streams.


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