Lun / User VM

[Gwi]

Hi!

We are actually planning a new project: we will soon provide one VM by user and it will be their workstation.

My concern is with the LUN assignement. We really need High performance and we know that the price for that is 1 vm / 1 lun. Right ?

Do we really have a lost in performance by having, i.e. 5 vm / 1 LUN ?

Thanks in advance !

- Gwi

[vmroyale]

Hello and welcome to the forums.

Have you seen the Performance Characteristics of VMFS and RDM performance study? Depending on the nature of the workload, you may find that the differences are negligible.

If you are looking into virtualizing many desktops, you may have to look at the reality of using VMFS. There is currently a maximum limit of 256 LUNs per ESX host, so if you had a lot of VMs you could hit the maximum. Another consideration is that the more RDMs you add, the more you complicate the management of your storage environment. Its much easier to manage 3 or 4 LUNs than 30-40 of them.

Good Luck!

[williambishop · Accepted solution]

By no means are you restricted to a 1:1 ratio. I've had servers people told me had to have maximum throughput, and I put them in with 2 or 3 others, only to find their definition of fast and mine were different, and later moved them into volumes with a dozen vm's(my definition of fast is over 400MB a sec constant).

Your performance isn't really determined by this, but rather by the array. That said, I never use a 1:1 ratio....it's unnecessary, and I've hundreds of servers and thousands of vdi desktops in vmware...including some that were migrated from big ibm iron (what we generally call a "heavy" server).

[Rodos]

Further to what others have said I would be more worried about your storage than VMFS. After all that LUN is going to sit on disks, how many, what size, what speed, what protection method and what other LUNS will be sharing those disks? If its real performance you are then going to want to look at your cache in the san controllers, as some boxen will let you segment the cache and adjust its block size to match. Then think, how am I going to monitor it?

Remember storage VMotion can be your friend. With VMware you are not locked into one config, its virtual.

All fun stuff.

Rodos

Consider the use of the helpful or correct buttons to award points. Blog: http://rodos.haywood.org/

[Gwi]

thanks !

I will read more about the cache in my san to find out the best way to configure it.

- Gwi