Question : Designing Luns and datastores

Hi,

Im in my last phase of our VM/SAN migration design, and I am having a little trouble understanding how to proceed with LUNS and datastore designs.

Eg, lets say I have one esx server, and I need to convert 3 physical servers to the virtual environment. How do I design the LUNS and datastores?

The physical servers have the following config

1. Window 2003 server, c: part 50 Gb, d: part 450 Gb, e: part 500 Gb = total 1 TB storage

2. Windows 2008 server, c: 1 TB, e: 500 GB = 1.5 TB

3. Windows 2008 server, c: 800 Gb, d: 200 Gb, e: 250 Gb, f: 250 Gb  = 1.5 Tb

Do I create 3 seperate LUNS on the SAN with a datastore for each that equates to LUN 0 = 1 Tb, LUN 1 = 1.5 Tb, LUN 2 = 1.5 TB, create a datastore for each and then create the VM on the datastore and partition the drives on the VM OS?

Or do I create one massive lun = 4 TB, create a single datastore and dump all the VM in there and then partition the drives as needed?

Or is there some other method alltogether than is "best practice"?

Lastly, do I create the ISCSI initiator from the ESX host itself through the "storage" tab or do I run the scsi initiator from the VM OS to the LUN on the SAN?

Thanks

Answer : Designing Luns and datastores

no - I'm saying that if you allocate the whole lot as a 15 drive raid-50, that your LUNS will span the entire raid-50 array (and in doing so, the three underlying raid-5 arrays).

a lun in the raid5 will only span that raid5. you cannot create a LUN in an array larger than the array.  
ESXi will allow you to run a single VMFS file system with multiple extens over multiple LUNS (not necessarily in the same array, or even the same SAN), but this is obviously handled at the hypervisor filesystem level, not the SAN.