Help SAN storage and VSPHERE 2TB limit

iamuser used Ask the Experts™
I have a physical machine that needs to be VM

From what I understand Vsphere/ESX 4 can only see max 2TB per volume but I can have multiple 2TB Volumes

My physical box has 2 drives in them

C: drive is 2 TB with 1.5 being used
D: drive is 4TB with 3.6 TB used.

How many I going to VM this box over? I don't have a volume big enough on the SAN that can hold the second drive.

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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

vSphere 4.0 has a 2TB-512 bytes limit for VMFS datastores as per the following document

Configuration Maximums for VMware vSphere 4.1

It also has a 2TB-512byte LUN and virtual disk limit is also 2TB-512bytes.

So you physical server, C:\ 1.5TB falls within these limits so that's okay, but the current drive D:\ limit and exceeds the limit. This may make this phyiscal server not an ideal candidate for virtualisation, but you could apply the following workaround, of wait for vSphere 5.0 and VMFS 5.0.

1. Use an iSCSI LUN on the SAN, create a 4TB iSCSI LUN, and present to the Microsoft iSCSI Initiator within the VM, this limit is defined by the size of NTFS.

Virtual disks and virtual RDMs are still limited to a max size of 2TB in vSphere 5.  It's just the storage LUNs that have had their supported max size increased (64TB is the new max).

Should clarify, when I say 2TB, I'm referring to the "2TB-512B" limit.
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kevinhsiehNetwork Engineer

Can you break the D drive down into multiple 1.99 TB volumes? that's that I would do, or move it all to an iSCSI volume that you directly attach to from the guest.


The 4 TB drive on the physical box is a singel raid 5 as 1 logical drive. So breaking is not possible

VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
use an iSCSI 4tb LUN on your SAN.
kevinhsiehNetwork Engineer

I understand that it is a single logical drive, but can you separate some of the shares or directories into separate volumes? Even if you had just a single share, you could break that up if you had some large directories underneath that could by physically moved over but could all keep the same logical UNC path via a local DFS root. That said, I agree with hanccocka that I would use iSCSI from the VM if that is available to you. That's how I connect to my file server, Exchange, and SQL volumes.
if you absolutely need one single data disk :
You could create 2x1.99 TB virtual disk for data and create a raid0 software within windows.
you'll end with 3 vdisk
1 for OS
2 for data in raid0
raid0 is not a problem within a vm when underlying hypervisor hardware is raid5

but you wont be able to use vconverter to transfer files.
i would recommend using a helper vm to synchronize data between physical to virtual and then detach the data discs from the helper vm to the converted one.

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