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Malawa
Contributor
Contributor

How many LUN with EVA 4100

Hi,

I have a EVA 4100 with two controlers. On it I have 2 LUN and on that about 20 VM each. I have read something about max handle on a LUN for Netapps and I can find a clear reference for an EVA.

My real questions are, how many LUN should I use on my EVA an how adding LUNs on the same HBA/Controler path will help performance since the data will go to the same path and the LUN will be on the same spindle ...

Thanks

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ablej
Hot Shot
Hot Shot

Normally you won't want more than 15 VM's per LUN. Too Many VM's per VMFS volume can cause SCSI Reservation errors. You will just want to size the LUNs appropriately based on disk sizes of you're VM's so you don't have to many VM's on each LUN.

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David Strebel

www.holy-vm.com

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Malawa
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Is it because of the handle limit per LUN ? Does the EVA 4100 have this kind of problem ?

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ablej
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Hot Shot

SCSI reservations are only used for specific operations when metadata changes are made and are necessary to prevent multiple hosts from concurrently writing to the metadata to avoid data corruption. So if you have to many metadata updates on a particular LUN you will get these SCSI errors. This is how VMFS file system works. With NFS you do not run into this type of issue. Since it does not use a VMFS file system.

David Strebel www.david-strebel.com If you find this information useful, please award points for "correct" or "helpful"