File <unspecified filename> is larger than the maximum size supported by datastore ‘<unspecified datastore>
I’ve been coming up against this issue for the last few days whilst installing some backup software for one of our customers. It’s highly frustrating and I couldn’t figure out why this was even happening. The data stores that this particular VM was running on had plenty of free disk space, and none of the disks exceeded the file size maximum for the block size on those disks.
What I didn’t know was, quite simply, that a VM cannot snapshot if it’s configuration file is stored on a data store with a smaller block size than one of it’s virtual hard disks. Now, I presume, that this is only the case if the virtual disk size is larger than the supported size of a file on the configuration files data store.
So, if you come accross this problem, just storage vMotion the configuration file to a data store with a larger block size, or at least to a datastore with the same size block size as your largest virtual disks’ data store. Run another snapshot, and “Hey Presto!” it should snapshot correctly.