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Dynamic VV expansion with VMware
https://www.3parug.com/viewtopic.php?f=18&t=1018		 Page 1 of 1
Author:  bradmc [ Wed Nov 19, 2014 5:37 pm ]
Post subject:  Dynamic VV expansion with VMware
This is a dumb question, but I can't seem to get it answered locally.

I have a 7400 with VMware servers direct-connected to it. Everything works fine. We added some disks, and the VMware admins want to expand the one VV exported to the VMware servers. Can I just edit the VV and increase the size to expand it? Some OS's don't support this, and I have asked the VMware admins, but all they can say is, "I think so", so I'm leery of changing anything until I'm sure I won't corrupt anything. The VMware admins would prefer one large VV instead of two smaller VV's exported to the servers.

I'm doing all of this thru the GUI, so speak to me in those terms. Thanks!

Brad (I'm not a VMware person)
Author:  Josh26 [ Wed Nov 19, 2014 6:08 pm ]
Post subject:  Re: Dynamic VV expansion with VMware
bradmc wrote:
the one VV exported to the VMware servers.
...
The VMware admins would prefer one large VV instead of two smaller VV's exported to the


They are doing VMware wrong. Multipathing is designed to spread load across multiple paths to the storage equally - across the various LUNs. A single LUN won't do this.
Author:  Schmoog [ Wed Nov 19, 2014 6:10 pm ]
Post subject:  Re: Dynamic VV expansion with VMware
Brad,

This should work just fine. I have done it many times.

If you are concerned, make a virtual copy prior to the change.

Anyway, the procedure is increase the vv size, rescan the vmware hosts, then right click on the datastores, click properties, and extend the datastore.

As far as multiple luns go, I think you'll be fine with one. Multipathing will still work just fine
Author:  afidel [ Wed Nov 19, 2014 9:33 pm ]
Post subject:  Re: Dynamic VV expansion with VMware
So for best performance on 4.1+ you want to keep to around 20 moderately busy vmdk files or 30-35 mostly idle vmdk files per data store, any more and even with VAAI, ATS, and multipathing and you'll start to run into performance problems.
Author:  hdtvguy [ Thu Nov 20, 2014 6:38 am ]
Post subject:  Re: Dynamic VV expansion with VMware
I agree with afidel. 5.x has continually improved the way files are locked on a datastore, but you still have other tuning parameters to consider such as disk.schedule for IOP contention on a LUN. You may want to look at SIOC as well. We tend to not like to go above 14016 VMs on a data store depending on the applications. We also spent a lot of time with HBA tuning as well as vmware disk.schedule parameters to make sure VMs can not monopolize a datastore. We are currently looking at SIOC to allow vmware to manager this for us. You can dynamically grow the VV in 3par and then the vmware admins can simple extend the datastore after they rescan storage. We have a site that has a 7400 with a pair of vmware hosts attached and we run around 4 datastores for 35 VMs. Most of our other sites with shared storage and 2 hosts we run from 2-4 datastores for 20-40 VMs.
Author:  bradmc [ Thu Nov 20, 2014 1:17 pm ]
Post subject:  Re: Dynamic VV expansion with VMware
Thanks!
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