Are Spanned VMFS Datastores 'safe' to use in a production environment?

[lgardian]

I've asked this question before but I did not get a clear answer.

I have a need to present a 8TB LUN to the VM running Win 2008 R2. The LUN this big is required to host medical images for archiving by the software vendor. The storage is Fiber Channel connected Net App FAS2040A. Currently my options are to use extends or buy CIFS license.

So the questions I have, are there any problems/issues/concerns with multi-extend VMFS volumes?

[a_p_ · Accepted solution]

Extents won't help in this case since the 2 TB limitation also applies to virtual disks. Even if you create an extended datastore, you would have to create multiple virtual disks and concatenate them to a software RAID 0 in Windows. I don't know the cost of the CIFS licenses and the impact on the disk space you need on the Netapp side, but to me that seems to be the safest way to achieve your goal.

André

[Dave_Mishchenko]

The use of extents are generally discouraged.  If you loose a LUN you don't have an idea of what data you would lose (if you're hosting many VMs on the datastore).

You'll still have the issue of getting that 8 TB into the VM.  Even with an 8 TB datastore, you'll still be limited to 2 TB virtual disk files.

[AndreTheGiant]

As written you cannot have a single vmdk greater than 2TB.

Use a lot of vmdk could be a way (and "join" them together with dynamic disks or mount points).

Andre

[piaroa]

How about presenting the 8TB from the NetApp to the VM via NFS?

[DSTAVERT]

piaroa wrote:

How about presenting the 8TB from the NetApp to the VM via NFS?

Sharing a share. The current NFS client is perhaps better than in the past but it has never been a screamer.

You seem so determined to have someone OK a less than ideal solution. ??

[lgardian]

I'm new to VM so this is a news to me. The 2TB VM VD kinda sucks. But oh well looks like I'll be begging for some cash to get the CIFS licence. The RAID 0 and dynamic disk are to risky for me, since is Windows based and we all know how good MS is .

I wonder how people are presenting a big disks to VMs (bigger than 2TB) without using windows tools...hmm.

Thank you for your responses.

[DSTAVERT]

Handling large 2TB virtual disks is problematic. These are single files. They become dificult to manage, move, backup etc. Making it an 8TB glob is even worse. Managing this at the SAN level is far easier.

[Marcj1]

If the image repository contains a folder structure instead of just a bunch of files you could use DFS within the guest to distribute the folders across multiple disks but have them appear as one giant disk.

[piaroa]

I must be missing something. I'm not trying to have anyone OK anything

[hairyfish]

I had the the challenge of presenting a 10TB volume to a server and the only way to do this (pre v5) was to create 5 x 2TB LUNs, format these as 2TB VMFS stores, then create 1.999TB disks (2TB is too big), then in the OS (Windows2008R2) span a volume across 5 disks using GPT.

This worked ok and haven't had any issues so far.