Configuring SAN Storage in ESXi - First Time Questions - VMDK or RDM for a 2TB File Share Server VM

[s1xth]

So...I thought I should turn the to communities for some assitance with this questions. I currently have 10 ESXi hosts all connected to local storage, so now I am ready to take the jump into SAN storage because I have a few VM's that need large amounts of space. I will explain what I want to do, and what I think I should do, I just want to know if this all sounds right and if anyone else could recommend a better way to configure.

I have a host right now that has 3 VM's running on it, and its a dual quad box. So I am going to add a VM to this box (Dell PE2950 III), it is going to be a large fileshare VM for server backups. I need 2TB of space for this machine, knowing that a VMDK at 8MB block size will give you 2TB, I am thinking of adding a Perc card to this box and ordering a Dell MD3000 with 6 500GB Near Line SAS drives. I am thinking of configuring it for Raid 5 and adding it as a datastore2 on this box and than creating a 2TB drive on the VM.

OR

Should I use RDM instead of VMDK? I am not to familiar with RDM, so maybe someone could point me in the right direction. Basically if anyone has a better idea for creating a 2TB fileshare server as a VM that would be great.

Thanks!

[s1xth]

Ok so with ESXi you definitly should not configure a LUN larger than 2TB or its going to remove the largest chunk. If you make a 3TB LUN it will only use 1TB, and ignore the 2.

Sent from my Nokia E71

[cainics]

We have a similar situation. I would recommend that you use RDM since it will give you a lot of flexibility and better performance too. You can expand your RDM LUN in future as disk space requirement increases.

Keep the server virtualized and add your data on the LUN partitioned as RDM.

-AS

Dazzle them with your intelligence or baffle them with your bullshit.

[Erik_Zandboer]

@cainics: An RDM is not flexible. It is a pain to perform hot backups on (physical RDM at least), and nowadays performance is almost on par with VMDKs. It is only the physical RDM which might perform better (but has the disadventagenot being snappable). Expanding the RDM is a no-go as well, as the proposed size is 2TB and you cannot grow any further anyway. The real pro for an RDM is that you could access the LUN directly from a physical windows box (no VMFS inbetween), but I wonder if that is going to outweigh the disadvantages in this case.

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[s1xth]

I think I am going to stick with the VMFS and just create a 2TB lun for this vm.