RE: ORION num_disks
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <exriscer@xxxxxxxxx>, "'Oracle-L Freelists'" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 12 Sep 2008 06:40:27 -0400
I'm missing why you think the number is not 1.
I'm curious why 4 LUNs were created - was it merely to keep the total size
down for a single LUN? (Some storage mechanisms parcel out various maximum
resource amounts per LUN, so there are reasons beyond the size is a single
LUN getting scary to carve up a stripe set into multiple LUNs. I'm not aware
of per LUN limits like that on Clariions. If there are some I'm always ready
to be enlightened.)
These disks have been linked together as a single interdependent unit of
i/o. Think about it this way: Can you predict whether any two simultaneous
i/o actions against this set of 4 LUNs will collide on a physical disk?
You have a single stripe set. (If by your description you mean the disks are
pairwise plexed and then striped across the four resulting resilient logical
drives, and then those are carved into 4 LUNs. It would be possible from
your description to consider a pair of two resilent drive raid groups. Then
you would have two independent units of i/o within the Clariion box and
possibly beyond depending on how the i/o controllers are set up and whether
sharing capacity on them can be nearly ignored [even with 90% headroom on
total throughput you'll get some collisions on request initiation.])
Regards,
mwf
_____
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of LS Cheng
Sent: Friday, September 12, 2008 5:28 AM
To: Oracle-L Freelists
Subject: ORION num_disks
Hi
Does anyone know what value should be used for num_disks argument when
running I/O stress tests with ORION?
For example consider I have a RAID Group within an EMC Clariion CX-700 SAN,
formed by 8 physical disks and striped using RAID 1+0, then from this RAID
Group 4 LUN are created and presented to the server.
What is the value for num_disks, 8 or 4?
TIA
--
LSC
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