One big LUN or severals LUNs ?

[Korvin32]

Hi,

Would you recommend splitting a 3 TB storage to several LUNs or will having one single LUN have no effect on performance ?

I'm using several ESXi 4.1 hosts (not in cluster mode - each one is independent)

thanks,

K

[golddiggie]

You'll need to have at least two LUN's there since the max VMFS datastore size is 2TB-512B...

LUN size is usually determined by what the VM's are, or will be doing, performance of the SAN/array, and demands of the VM's on the array... I would, typically, go for a 500GB to 1TB (max) LUN size in a production environment. If you need to have large volumes on a VM, then it's probably a better idea to make a seperate LUN for that VM to directly connect to (either iSCSI target or RDM) and share it that way. iSCSI targets will let you get past the 2TB-512B limitation for a shared volume within a VM.

Another consideration is how the array/SAN lets you carve up the storage. A good amount of local datastores( DAS) can only present two LUN's per array. The better SAN's will allow you to carve the total storage into as many LUNs as you need, and whatever size works best for the task...

VMware VCP4

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[Korvin32]

the max can't be 2 TB since I currently have a single 3.4 TB datastore ...

I'm wondering if splitting it up will have any performance benefits or not

[kastlr]

Hi,

vSphere is only capable to handle LUNs of 2 TB (-512B), but a datastore could be build out of multiple LUNs.

If your datastore is 3.4 TB large, then you're using at least 2 LUNs.

Your question couldn't be really answered, as it depends on several different things.

More LUN's are better to handle an higher IO load than a single LUN, but an extended datastore is configured as a concatenated filesystem.

But this doesn't mean that using an extended datastore is a bad thing when it comes to performance.

When you create VM's on such a datastore, VMware does have a mechanisum to spread the VM's on different LUN's building that datastore.

So in fact it's neither striped nor concatenated.

Hope this helps a bit.

Greetings from Germany. (CET)

[AWo]

I'm wondering if splitting it up will have any performance benefits or not

That depends on your storage type and infrastructure. More LUN's can mean you have more I/O queues and more paths available. In this case more LUN's mean more throughput.

AWo

VCP 3 & 4

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[Korvin32]

thanks guys - this helped a lot

I'll investigate this matter further once I can play around with the LUNs ... :smileyhappy:

K

[AWo]

If you describe what you have/get we might give you some hints beforehand.

AWo

VCP 3 & 4

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