ESXi 5.5 rdm local storage 2tb limit ?

[Digian]

Hi all, I have a new Haswell based server with an unsupported Intel Lynx Point Sata controller, since its unsupported I cant do DirectPath I/O so instead im trying to raw device map each local sata 3tb hard disk to a guest.

Can somebody please clarify for me whether a 2tb limit I have been reading about, applies to my situation ? Since the disks im trying to raw map are all 3tb and I am seeing odd results.

Esxi can see my disks and ive setup a passthrough using the vmkfstools command like so:

vmkfstools -z /vmfs/devices/disks/t10.ATA_____ST3000DM001 /vmfs/volumes/ssd/rdm_ST3000DM001.vmdk

Problem is, when they appear in windows, im seeing some really weird stuff like it says the raw disk size is 512 B / 16.0 EB (exa bytes) .... wtf ?

Yet it shows the correct 2.73tb (3tb) volume.

Very confused and concerned whether these disks will end up corrupt ???

[tomtom901]

A RDM is officially not supported on local storage (VMware KB: Raw Device Mapping for local storage), but since it sees the disks correctly (or at least the disk size) I think it should work. Do you have existing (important) data on this disk?

The RDM max limit size is 64 TB and it was like this since ESXi 5.0. The 2TB max you're reading about was for a VMDK file on ESXi 5.0 and 5.1. They stretched that up in 5.5 to 64 TB, so why don't you use the disk as a datastore and configure a VMDK disk for the VM?

[Digian]

Disk has data on it and so would prefer not to format, also raw device map is theoretically faster than vmdk method in my use case. Additionally, leaving in NTFS raw device map means I can remove disk and access easily elsewhere if necessary.

I believe VMware should correctly report capacity and allocated space of device, since I am using correct GPT format, so there must be a problem in Esxi still ... not willing to risk corruption or trial and error of wiping disk to find out.

Reporting 512 b capabity and 16.0 eb unallocated space is clearly a problem.

[nyadav]

Digian,

Can you try adding the local SATA disk as a SATA disk in your windows VM. From the screenshot I can see that you added it as a SCSI disk.

[sludgeheaddf]

The resolution is to upgrade VM hardware version to 10 (ESXi 5.5), add a SATA controller (limited to HW v10), add the raw device map to the SATA controller rather than the default LSI SAS. There appears to be some difference between manufacturers firmware and how the 512b sector emulation works.

[piliran]

@sudgeheaddf Can you please expand? I can't seem to find a way to add a SATA controller to an RDM - it seems to only work with local disks or virtual files (no RDM)s. I've tried manually editing but without success.Cheers!

[piliran]

Never mind - found the solution (manually edit or use vSphere Web Client).

[allxi]

esxi 6.0.0 it fix

Support for virtual machine disks larger than 2 TB in VMware ESXi 5.5.x and 6.0.x (2058287) | VMware...