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August 8th, 2012 15:00

500gb or 1tb lun

i am not sure if it makes a difference but

is performance the same if I created a 1TB rg and a 1TB lun under it

vs

a 1TB rg and 2, 500gb luns under it

13 Posts

August 9th, 2012 01:00

I assume you have a CLARiiON or VNX array on which you make a RG?

In that case, the LUN will be owned by one Storage Processor.

Thus by creating two LUNs in one RG, you can assing one LUN to each SP, balancing resources of the array.

An additional benefit could be that you have more queueing towards the array, but that is probably not the limiting factor.

Best Regards,

Hans

12 Posts

September 5th, 2012 15:00

Since this is on the "Everything VMware..." community, I will assume VMFS's presence.

Creating a single VMFS volume out of two LUNs doubles the number of device queues in each ESX host.  Whether you reaggregate those LUNs via extents or just manage two VMFS volumes instead of one, a host that addresses both of the can place twice as many commands in flight as the single-LUN option.

However, the benefit of a larger queue is not normally visible. VMware has shown the default queue configuration delivering hundreds of thousands of IOPS.  Since the single raidgroup configuration you propose will obviously be the bottleneck you'll see no difference from the increase in aggregate queue capabilities.  So, save yourself the headache of managing multiple LUNs and just create one 1 TB LUN.

Scott

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