Using OpenFiler to create 2 TB+ NTFS / NFS datastore over VMware

Hi All,

I'm about to create a very large file system for Windows Server and client to use (NTFS), by using Openfiler as the iSCSI initiator. [any other free appliance is also great]

Can OpenFiler that is deployed on my VMware ESXi as VM presenting / using the unformatted 2 TB+ datastore as the RDM ? [Because of the VMFS limitations it cannot recognize or use > 2 TB datastore]

My situation is to utilize the unused 6x 500 GB SATAII disks that is on my Dell Power Edge server, all of the VM is on my SAN.

Any kind of help and suggestion in presenting the unformatted LUN greater than 2 TB to the Windows Server would be greatly appreciated.

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Openfiler is good, as is Freenas ( or Nexenta (

RDM's can only be used as an RDM when they are remote from the server.  VMWare does support more than 2tb but you have to join them together using extends to give you your maximum.

6 x 500gb as RAID 5 will give you around 2.9tb which is good.

Don't forget that under Windows you can extend multiple volumes into could use your iSCSI VM and create two iSCSI LUNS of around 1.4tb each and extend them under Windows.

One thing to remember - you have a SAN for a reason and one of those is probably for redundancy.  Putting this onto your single server will introduce a single point of failure for your Windows storage.
jjozAuthor Commented:
ah.. ok, so in this case i've created the VMFS LUN > than 2 TB, and now I shall begin to install OpenFiler and then add 2x1TB HDD (VMDK) into it ?

Do I understand this correctly....

You have a Dell server that you want to run Openfiler on to allow it to be an iSCSI target for your Window VM to use so that your Windows VM can have larger than a single TB disk to use instead of using a VMDK for it. Is that correct?  If it is then yes you could do that however I would caution on using snapshots on the Windows VM. (I haven't read about that but I would assume that a snapshot could be potentially disastrous if you reverted to it. Suggest more research on that.)

Or is your ESXi running on the Dell server directly?
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jjozAuthor Commented:
Q:Is your ESXi running on the Dell server directly?
### my ESXi is installed on USB drive which is attached to my Dell Poer Edge 2950-III server, so that i can utilize th maximum 6x500 GB disk space.

Finally, here's what I'vegot, it is configured on my ESXiVM with the following Openfiler configuration:

R/W Mode: Write-thru
Transfer Mode: blockio

hopefully I'm on the correct path.
So assuming that your Openfiler and the Windows VM are on separate hosts I can understand why you want to do this. If they were running on the same host, then I would suggest giving the Windows VM the raw disk mapping directly.

So the answer to your original question Can you do this?  The answer would be YES.  The question is should you do this? I am not clear on that answer.
jjozAuthor Commented:
"If they were running on the same host, then I would suggest giving the Windows VM the raw disk mapping directly."
### yes this Openfiler is running on the ESXi server but the Windows Server that is going to use this storage is  a physical server.
Ahhh. OK. Thanks for clarifying. Then yes the RDM for an Openfiler VM makes much sense and I would give it a try.  

Thoughts on RDM:
-Bigger than 2TB and simpler to get going
-Little more difficult to backup Disaster Recovery image of the VM.

Thoughts on multiple VMDK's from 2 VMFS file sytems on the RAID 5 disks put together with extents in Openfiler:
-Easier portability of the OpenFiler VM to another host in future.
-Higher risk of data corruption if one disk times out, but may never be an issue.

I would rather put the extents together in OpenFiler than putting them together in Windows. If the VMDK's are all coming from the same spindles don't put the VMDKs together with a RAID 0 as that will slow things down.

Note: I would increase the timeout of the Windows server in regards to the iSCSI target lun. Here is one blog article about it. I am sure you can google a lot more.


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jjozAuthor Commented:
yes, thanks for the explanation sir, I do appreciate it so much.

Little more difficult to backup Disaster Recovery image of the VM. --> this is a fileserver for backup purpose so no need to back it up again :-)
jjozAuthor Commented:
thanks for the responses.
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