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From James Chris Beaver <>
Subject RE: Question about disk optimization in ATS.
Date Wed, 14 Dec 2011 21:11:38 GMT
Thanks for the insight John.

When you say no RAID of any kind - I was going to format 2 large hardware raid 5 sets for
redundancy. The raid 5 sets would be comprised of 3 * 146GB SCSI drives (as there are two
raid 5 sets there are 6 disks in total).   Are you saying that it would be best if I just
presented 6 (un-raided) disks to be formatted as raw disks?

Kind Regards


From: John Plevyak []
Sent: Wednesday, December 14, 2011 4:04 PM
Subject: Re: Question about disk optimization in ATS.

Under heavy forward proxy load, ATS tends to be seek limited which favors lots of disks. 
As ATS has its own recovery mechanisms it is best *not* to use raid5 or any raid, but just
a bunch of raw disks listed in the storage.config.

ATS needs to have small block sizes, so don't use raid or stripe with a volume manager as
this will degrade performance.

If you use a disk which has large blocks (3GB disk) then you may need to set the flag to force
ATS to use a larger internal blocks size which results in some waste of disk space.

If you are reverse proxy and have a small working set and a good size RAM cache you may not
be disk limited, in which case you have more flexibility.   Even in this case I would
still suggest not using raid or striping.


On Wed, Dec 14, 2011 at 12:09 PM, James Chris Beaver <<>>

Hello Folks,

I am looking for information in regards to the best way to optimize disk in ATS.  I understand
that the application uses raw disks however what is the best way to lay out those disks? 
Is it best to have more than one cache disk?  I am inclined to put up more than one hardware
raid5 volume and then format them as raw disks for ATS to make use of.  Is there a "rule of
thumb" when it comes to disk sizing?  What block size is best (large of small)?  For example
if you have to large of a disk(s) will that slow down ATS as it must spend time keeping track
of very large caches?

Any guidance is greatly appreciated.


Chris Beaver
UNIX Systems Administrator, ITS - Algonquin College
1385 Woodroffe Ave
Ottawa, ON K2G 1V8
phone: (613) 727-4723 x 5385<tel:%28613%29%20727-4723%20x%205385>
fax: (613) 727-7719<tel:%28613%29%20727-7719>


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