Presenting LUNs across ESX Clusters

[vmproteau]

We have 2 ESX Clusters (3.0.2 Update 1). One cluster has 3 Hosts the other has 2 Hosts (each will likely grow). I standardized on a 400GB LUN however; I started to think about best practice for presenting LUNs to these Hosts.

I have presented a generic templates LUN to all my hosts. As I began presenting others, I decided to standardize by presenting any new ESX LUN to all ESX Hosts. I considered presenting each LUN only on a cluster by cluster basis but, I figured standardizing by presenting them to all Hosts would allow me more flexibility when deciding where to put a new VM (regardless if it turns out some LUNs end up only being used by one cluster or the other).

Before I get to far along I wanted to post it here to see what others are doing. It seems the only downside is that, Hosts would be presented more LUNs than they would if I kept LUNs seperated by cluster. I understand the 128 LUN limitation per host but, my job will be virtualized before we get there. Even so, is there any performance or other downside as a the number of LUNs a Host is presented increases (i.e. Would an otherwise identical Host perform any differently with 50 Luns presented as opposed to 20)?

Any other comments or considerations would be appreciated.

[Yattong · Accepted solution]

Guess all you need to bear in mind is that you will be using the service console's memory to do a lot of things

e.g. remember LUN id's pathing, ensuring all paths are up and all vm's in a cluster etc...

You can do a 'free -m' to see what memory is in use and what you have left.

May want to push up the sc memory to 800MB too, if you havent already.

We're currently have 45 Luns presented to 16 esx servers and seems a little congested whenever we want to do any other tasks, e.g. rebalancing vms across luns. So to remedy, we are multipathing all luns.

Good luck

[vmproteau]

Thatnks for the detailed response. I had already adjusted my SC memory to 800MB during installtion. The "free -m" command was new to me. Thanks for that. I do notice that I don't have much free (26MB).

Should I push the SC memory even higher than 800MB?

I adjusted my swap partiion to 1600MB during installtion. If I push SC memory above 800MB is irt a problem if my swap file remains at 1600MB? I've read somewhere that best paractice is to make that swap partition double the SC memory?

[Yattong]

max SC memory is 800MB.