Storage vMotion vs LUN resize

vSphere 6.7 (storage vMotion set to manual)

I inherited an environment where all the LUNs (NetApp SAN) were sized at 6TB.

The environment is growing, at least a few (2-5 of 100) VMs are constantly growing and I find myself resizing their (usually Windows Server 2012 R2) disks twice a year.

I have a few VMs that are 4TB, so I'm starting to get storage warnings on a few datastores.

I've done a few storage vMotions on smaller VMs and the performance seems pretty terrible: some of my applications actually react to the SAN latency.  Sigh...

I guess the answer is obvious?  Do I:

1. Create a few bigger LUNs (10TB) and move those bigger VMs to it?

2. Just resize my existing LUNs to 10TB, and then I don't need to move any disks?

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3 Replies

Hi marcoshaw​ hope you are doing fine

I would go with option 1 since there is less risk involved.
Are you using thin provisioned disks?

Warm regards


Most of my disks are thick, but this is how I inherited things.

I'm not sure about #1...  When I do a svMotion, my applications are impacted and moving such a large VM could take a few hours and cause some applications issues.

I think I've determined that when my SAN has more than 5k write IOPS, the SP/CPU is almost at 100%.  This seems to cause latency accessing the disks, thus my applications begin to react negatively.

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Even when you do a single storage vmotion?
All apps are impacted?

Can you tell me about your storage infrastructure?
have you ran esxtop and checked storage and HBA usage?

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