Hi William,
Thanks for the reply. Not sure how to get this track cach size?
What's confusing me most here is that the values are so different between
the two arrays. They're identical models set-up up the same and with the
same number of disks allocated to the servers - sorry, forgot to mention
they're in an HA pair using VCS. The only difference is that IBM_SHARK0 is
local to the server where the workload is currently running, and IBM_SHARK1
is in another building about 1.5KM's away. It's this disparity that is
confusing me and making me wonder whether an issue we are seeing is being
caused by this, or if it's an indication of an issue, though I've been
informed by our storage people that there's nothing wrong with either
array.
This is certainly not something we've changed so I don't know if
VxVM/DMP is throttling things back because it's seeing an issue. I have
seen messages in the /etc/vx/dmpevents.log file for disks in the IBM_SHARK1
array reporting 'Throttled Path' and then 'Un-throttled Path' and I'm
trying to work out if the two are linked.
Cheers
Phil.
William Havey
<[email protected]
m> To
[email protected]
26/07/2012 15:48 cc
Subject
Re: [Veritas-vx] Question over DMP
partitionsize
Partitionsize is in play when the iopolicy is Balanced, which is the
default policy. You have Balanced.
It is defined as "The partitionsize attribute: Each successive I/O starting
within in this range (default is 2048 sectors) goes through the same path
as the previous I/O"
The man page has "Takes the track cache into consideration when balancing
I/O across paths"
What is the track cache size on each array? Seems that the partitionsize
should be the same value as the track cache size.
On Thu, Jul 26, 2012 at 7:09 AM, <[email protected]> wrote:
Hi,
I'm trying to understand why one array has a wildly different
partitionsize value to the other...
fuj411:/root# vxdmpadm getattr arrayname IBM_SHARK partitionsize
ENCLR_NAME DEFAULT CURRENT
============================================
IBM_SHARK0 2048 2048
IBM_SHARK1 256 512
fuj411:/root#
Both arrays are IBM ESS SHARK 2105's which are active/active and
operating
in a Balanced i/o policy...
fuj411:/root# vxdmpadm getattr arrayname IBM_SHARK iopolicy
ENCLR_NAME DEFAULT CURRENT
============================================
IBM_SHARK0 Balanced Balanced
IBM_SHARK1 Balanced Balanced
fuj411:/root#
The server is a Fujitsu PW850 running Solaris 10 with VxVM v4.1 MP2. The
volume are mirrored between the two arrays.
I'm trying to get a better understanding of what this means and why it
would be so different between the two arrays. Any help greatly
appreciated.
Cheers
Phil.
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