LUN ID numbers

[njd62495]

I have a few ESX 3.5 servers that are connected to about 15 LUN's on the SAN.

Do the LUN numbers for the assignments on the host servers have to match?

For example LUN1 is presented to ESX host A, B, and C. Host A has LUN1 assinged with LUN#1. Host B has LUN1 assigned with LUN#4, Host C has LUN1 assigned with LUN#22.

They are all accessing the same disk (LUN1), but will the different LUN#'s cause any issues?

[AndreTheGiant · Accepted solution]

The LUN id is relative.

Is the UUID that identify a Volume.

Andre

**if you found this or any other answer useful please consider allocating points for helpful or correct answers

[kjb007]

LUN id's should match across the board. If for nothing else, then for your own sanity, when you are troubleshooting what LUN is actually which LUN that is in use. If you can keep them consistent, you should. After the initial vmfs filesystem creation, the UUID/NAA is used to identify the LUNs, but I have seen instances where mismatched LUN id's caused certain LUNs to appear as snapshots and therefor disabled by ESX. If they are presented in the same order, and all your hosts have the same LUNs (at least for the cluster where you add them), then the LUN id's should end up the same, even though the LUN id's were not directly added from the storage side.

-KjB

VMware vExpert

[njd62495]

Thanks. I'm doing clean up work so I really cant unpresent LUN's and then re-present them will matching LUN#'s to get them all consistent so I'm doing my best now to keep everything clean.

I've also seen the snapshot issue as well. Not fun to deal with...

[AndreTheGiant]

You're welcome.

Andre

[morciod]

Does the LUN id still matter when clustering in ESX v4 when on a SAN

Debbie