Best practice for the number of luns per esx host?

[AmaliaNL]

Hi,

I know there is a maximum of 256 luns per host, but is there a best practice for the number of luns per host? We are using a HP EVA 8000 and are scaling up the hosts. An HP best practice is to put a max of 10 vm's on a datastore. Since we can accomodate lots of vm's on our 10 node (64Gb, 2x Quad core) HA / DRS cluster we will need more then 40 luns, presented to all of the 10 hosts.

Thanks.

[weinstein5]

It all depends - how many HBAs will you have and what type of load will determine how many LUNs an ESX Host should have -

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[AmaliaNL]

Thanks, I know, there al all kinds of circumstances that the actual number of luns will depend on. I am not looking for an exact answer, I am interested in other peoples experiences. We are using two hba's (Qlogic) per server, set the qdepth and DiskSchedNumReqOutstanding to 64 and load balance the paths over the hba's.

[Rodos]

10 is low, Chad from EMC mentioned they are seeing around 20. Its going to depend on the sizes of your systems too.

40 is an okay number of LUNs to zone to the host, your limit is 256.

You may find this post helpful .

Rodos

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[kjb007]

How many paths will you have to your storage? The only thing you may run into is out of memory/low heap error messages that will keep some LUNs from being seen. I've seen this happen to others, but the value VMFS.MaxHeapSizeMB, adjusted above the default (16) to a higher value helped alleviate the issue. Other than that, now issues. My current path/LUN count is around 200+ serveral LUNs seen over several paths (they each count)

-KjB

[Texiwill]

Hello,

More LUNs implies more simultaneous metadata operations. You can easily have 12-15 VMs per LUN depending on the size of your LUNs. You could have more based on utilization. Remember you really do not want to fill a LUN past 90% and 80% is the average.

Best regards,
Edward L. Haletky
VMware Communities User Moderator
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Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.
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