VMFS or RDM for ESX3.0

[helpme_]

Hi

I am building a VM file server for our production environment instead of a physical server which we usually use. The way we have our file servers set up is to have a number of LUNS presented from our Clariion CX3.-80s and we then mount the volumes in folders for example C:\fileshares\fileshare1, C:\fileshares\fileshare2 etc. I want to have this same setup with the ESX VM but i'm not sure on the best way to do this. Should I create a VMFS for each LUN i present from the SAN or would it be better to use a RDM? Can a whole VMFS volume be presented to a VM as one disk which it would see in disk management?

Can anyone help me with this?

Many thanks

Joe

[mike_laspina]

Hello,

There are two possible directions I would consider here.

1) Create standardized VMFS stores (I use a maximum 500GB per VMFS standard) for the VM 's not for a specific purpose but more for all the VM's that the resource will host. Then based on the size of the Current LUN's either use RDM and map them to the ESX hosts for use on the VM's. I limit my vmdk's to 100G.

2) If the LUN's are less than 100G you can just define them and move the data over.

Issues:

Performance. You should really split the I/O over two SAN paths.

Backup. Consider your backup time windows, type and resource usage when placing large vmdk's on a volume.

[helpme_]

Hi Mike

Thanks a lot for your reponse. Basically, what i have done so far is I have one VMFS volume where my VMDK image will reside for this server then the main issue is that i will need to present approx 12 500GB luns to this server which will be mounted volumes on the host O/S (Windows 2003). I wasn't very clear in my original description of the issue but basically, there is no data which i will need to migrate onto the VM. It will be a fresh server but because of the nature of our business, we need 500GB volumes on the server, to which data is dumped fairly regularly over a 24 hour period (it's a processsing environment). I really don't know what the best approach would be.

[mike_laspina]

With 500GB LUN's I would present them as RDM LUN's, there is very little performance difference between RDM(slightly better) and VMFS but you will have better control of your I/0 paths with RDM.