How Big Should my iSCSI LUNs be for VMware?

[vmw9]

How big should my iscsi luns be for vmware? ARe there any considerations to take ?

[rugby0134 · Accepted solution]

VMware 5.5 supports a VMFS datastore volumes up to 64 TB in size.  The nimble Array can support a volumes size up to 128TB.

So you have to ask yourself, "How big do I want to go?"

I don't see people making datastores much larger then 2 TB except when used specifically for large Databases, or shares.   The Nimble snaps are amazing for recovery and clones, so must of the rules around RPO and RTO are removed with a Nimble array.  The reasoning behind a 1 TB LUN was that you can restore a 1 TB volume from tape faster then a 2 TB Volume, and a 500-GB volume even faster.  But if your going to be recovering from a SNAP or replicated SNAP, then the recovery time the the same no matter the LUN size.

But - if your going to run external backup software - this is were you might want smaller Volume. Because of that time to recover, and backup files.

The best advice I can give is, "what ever your comfortable with for recovery times, and that your backup software can complete within your SLA".

[vmw9]

hi thank you. makes a lot of sense.

just wondering, the io in nimble is overall the same across all volumes right since its one big system? or would it be changed across different volumes?

[rugby0134]

You're correct. The performance and storage is a share resource available to every server connection.