The VMware datastore LUN 2TB (well, 1.99999 TB) size limit

Fri, 24 Sep 2010 16:00:15 +0000

I started migrating our physical machines to VMs using VMware a few years ago and the first problem I ran into is still the most annoying one: the size limit for LUNs is, per VMware’s docs, (2TB - 512B). That’s 512 bytes shy of 2TB, so basically 1.99999 TB, or 2047.999 GB. So when I create a new LUN for a datastore in the SAN the max size is 2047 GB. Now, as the VMware KB article states, this is a limitation of SCSI, not VMware per se, but that doesn’t make it any less annoying. When I first setup ESX, I created a 5 TB LUN for the datastore. It showed up in vCenter as 1 TB. After some Googling I learned of the 2 TB limit – the usable space is basically usable space = (size of lun) % 2TB, where % is the modulo operator – and found something suggesting using extents to expand the datastore across luns. I did that, but I later learned that there seems to be a consensus that extents should be avoided.

2tb on Evan Hoffman

The VMware datastore LUN 2TB (well, 1.99999 TB) size limit