Unable to create filesystem (mkfs.ext4) 2TB CentOS 6.5 VM

Question

All, We have been having trouble creating disk volumes larger than 2TB on CentOS machines in our lab environment that consists of Hyper-V 2012 R2.
Today we came a step closer with the help of
http://social.technet.microsoft.com/Forums/windowsserver/en-US/bc1ee7e7-dcaf-455b-baec-01e6128ddd28/action?threadDisplayName=unable-to-create-filesystem-mkfsext4-on-large-gt-2tb-gpt-virtual-disk-using-linux-vm - which suggests mkfs with the '-K' option.
This has created a mountable logical volume, however it only registers as 2TB, rather than the actual size of 4TB. I notice the article is over a year old. Has there been any fixes?
The alternative would be multiple 2TB drives..

Answer 1

As part of the product team that does Linux on Hyper-V, we've recently spent some time investigating this problem.  It occurs because Linux issues a SCSI "WRITE_SAME(16)" command, which is not implemented by Hyper-V.  WRITE_SAME(16) is optional
in the SCSI spec, so it's OK that Hyper-V doesn't implement it, but the problem is that Hyper-V doesn't return the correct error code and sense info to indicate that it's unimplemented.  With the correct error code from Hyper-V, Linux would use alternate
SCSI commands and everything would work.
We're looking into possible fixes.  Hopefully in the next couple of weeks we can have an update on what to expect.
We believe Ubuntu 14.04 actually works correctly on Hyper-V due to a complicated set of other reasons.  RHEL 7.0 does not work, and the other file system types don't typically avoid the problem either.
Michael Kelley, Lead Program Manager, Open Source Technology Center