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bovc
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SAN config for ESX3

Hi,

Does it matter what LUN ID I give our different LUNs?

We have 6 ESX-servers and 3 SANs - each with 2 LUNs. Now, on each SAN-box the two LUNs are named 1 and 2. Shouldn't this be able to work since the LUNs are on different SAN boxes? Or is it a bad thing?

The reason I ask, is because we've seen some odd things over time. Usually finding solutions, but they just keep coming.

We have the DisallowLUNSnapshot set to 0.

Rgds,

Rasmus

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mpverr
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The same LUN must be presented with the same Lun ID to all hosts. But I believe you can have the SAME LUN ID from different LUN that are are on different SANs.

So -

SAN 1

LUN1 - ID1

LUN2 - ID2

SAN 2

LUN1 - ID1

LUN2 - ID2

everyone host needs to see SAN1/LUN1 as ID1 and SAN1/LUN2 as ID2

so on and so on.

Each SAN is a different target from VMware perspective. So YES - you can (and need to ) have the same LUN presented to all host as the same LUN. If you have multiple SAN then YES - you can have a LUN on one san have the same LUN ID # as that on another SAN. Because the storage processors (targets) are different VMware handles this fine. We do this.

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admin
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Presumably they're all connected via the same HBA though? Even though it should work, I'd set the LUD IDs to be unique, I've not done it with FC but have seen problems on the iSCSI front when connecting to two iSCSI SANs using the s/w initator and having the LUNs each box presented as 1&2 - basically it only sees the first SANs LUNs and the second ones are not mounted.

It's also important that you present the LUN IDs in the same order to each ESX server.

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Paul_Lalonde
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What mittell says is absolutely critical. If one ESX server sees VMFS volumes presented to it using LUN IDs that are different from the other ESX servers, you'll end up with VMFS volumes showing up as snapshot volumes and can't mount them.

Paul

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bovc
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I get your point.

But the problem is not whether all esx servers sees each LUN with the same ID, but rather if each servers can see 6 LUN which are not named 1-6, but 1 and 2 (pr. SAN box)?

It's a little difficult exlaining it Smiley Happy I hope you understand.

Rasmus

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bovc
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To further explain:

SAN01: LUN1 + LUN2

SAN02: LUN1 + LUN2

SAN03: LUN1 + LUN2

Total: 6 LUNs.

We have 6 ESX servers, and they ALL see each LUN. So what I was trying to ask, was whether this could conflict? Cause basically each server will see 3 different LUNs all named LUN1 - can they tell the difference?

The LUNs are placed on different SAN boxes with seperate IP's, controller, etc. So basically there shouldn't be a problem - correct?

Rasmus

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bovc
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Anyone?

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bovc
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Hi,

I really need an answer on this. Isn't there anyone out there who can help me?

The basic question is just whether or not SAN LUN ID's need to be unique on a global view, or if it is enough that the ID's is unique on the individual SAN boxes.

Thanks in advance.

Rgds,

Rasmus

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mpverr
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The same LUN must be presented with the same Lun ID to all hosts. But I believe you can have the SAME LUN ID from different LUN that are are on different SANs.

So -

SAN 1

LUN1 - ID1

LUN2 - ID2

SAN 2

LUN1 - ID1

LUN2 - ID2

everyone host needs to see SAN1/LUN1 as ID1 and SAN1/LUN2 as ID2

so on and so on.

Each SAN is a different target from VMware perspective. So YES - you can (and need to ) have the same LUN presented to all host as the same LUN. If you have multiple SAN then YES - you can have a LUN on one san have the same LUN ID # as that on another SAN. Because the storage processors (targets) are different VMware handles this fine. We do this.

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