Snapshot/Block Size Limitation

jenuster

Limp Gawd
Joined
Mar 8, 2011
Messages
154
When I try to take a snapshot of a VM that is running ESXi 4.1 I get an error saying that


Error: File <unspecified filename> is larger than the maximum size supported by datastore '<unspecified datastore>

After doing some research VMware states this is an error that you get if your VMDK files are larger than the size that's supported by the block size of the datastore. Now the VM in question is provisioned with 2 256 GB drives. But looking at the datastore of the VM, the size of the VMDK's are over 268 GB. Question I have is how is the VMDK which is provisioned for 256 GB 12 GB's greater than that?

I'll be upgrading them to ESXi 5 very soon so this problem will goaway but was just curious.
 
Ignore what the browser says - it lies.

Snapshots have overhead. Max snapshot file size is disk size + overhead.

For a 1MB block size datastore, that's about 4G of overhead max, thus the max size of hte delta would be 256+4 = 260

260 is past the max file size, and would corrupt, so now we save you from yourself and block it :)
 
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