From: Clifton, Pablo (Pablo.Clifton@BCBSFL.COM)
Date: Fri Jan 17 2003 - 14:40:45 EST
Bill-
More LUNS = more hdisks/vpaths presented to AIX = more overhead for LVM
commands = longer failover times for HACMP.
BUT- if you want REALLY good performance from the ESS (100MB/sec reads+),
you will want to make a filesystem STRIPED VERTICALLY across LUNS on
DIFFERENT ranks(8packs).
If a filesystem is located on 1 LUN for example- then the performance will
be limited by the speed of a single 8pack(rank) which is typically MAX
45MB/sec for reads. If MULTIPLE hosts are using LUNS on that same RANK-
then performance will be even less.
I recommend making a Volue Group with LUNS all the same size if possible
from different 8packs(ranks). If you use something like 10 ranks- you will
be fine and LVM commands will not take much longer.
-pablo
--
Pablo Clifton
UNIX Tech Services
> * pablo.clifton@bcbsfl.com
> * DCC603-F212
> * 904.905.7116/ 210.287.4021 cell
-----Original Message-----
From: Bill Verzal [mailto:Bill_Verzal@BCBSIL.COM]
Sent: Friday, January 17, 2003 11:15 AM
To: aix-l@Princeton.EDU
Subject: ESS and LVM considerations
Hi *,
I am going into a meeting with our SAN team in about 45 minutes. I've been
pouring over Redbooks all morning to try to find information on something.
Hopefully the synergy out there will help.
Is there any best practice of documentation out there that says anything
like:
When carving a LUN in the ESS, using fewer BIGGER LUNs is more
efficient than more SMALLER LUNs.
I can see where AIX would have more overhead, but is it worth it ?
Thanks, Bill.
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Bill Verzal
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