ESXI 5.1 Thin provisioning
Posted on 2013-11-20
I'm hoping you can clear up some issues I'm having with VMware/ESXI. We have an Exchange VM running on an ISCSI SAN using ESXI 5.1 and VMFS 5 using block sizes of 1MB. The Datastore where the volume is located is 4TB in size, the Exchange VMDK file is in thin provisioned mode a provisioned size of 2.02 TB with 216 GB in use and the data store has 3.67TB free.
The issue is occurring when we try to take a snap-shot using either VCentre Server or using the Veem backup tool, we get the following error; "File <unspecified filename> is larger than the maximum size supported by datastore <unspecified datastore>". I have looked at various internet posts and they indicate various reasons why this might occur. And it looks like the issue is either one of two things; because the provisioned size of the VMDK file which is just over 2TB, although 2TB was selected when it was setup, I have seen posts that suggest that the max size of the VMDK file needs to be slightly less than 2TB
The other reason might be because there isn’t enough disk space available to complete the snap-shot despite the datastore indicating that there is 3.67TB available, this might be because this reading is based on disk space used where the snap-shot calculation is based on the provisioned size, not the space physically used?
So in short, is the problem that there isn’t enough disk space because the "provisioned" size is too big for the snap shot to fit in the datastore, or is it because VMware allowed me to create a VMDK file just over the 2TB threshold.
At the moment we're not getting any snap-shots or backups which we need before pushing some Exchange 2013 updates through.