Snapshot consolidation is the process of merging the content of all of the snapshots to the base disk. We have seen snapshot consolidations fail for various reasons. For instance, a backup appliance that hot adds the VMDK to its proxy server to back up its content should ideally remove the hot-added VMDK and issue a delete operation on the snapshot it created. If, for some reason, it fails to remove the hot-added VMDK, then all subsequent snapshot delete operations that it issues will also fail. This is because the file is in use.
If this goes undetected, then you will be left with a lot of snapshot delta files, all of which will eventually use up a lot/all of the free space on the datastore. Things get worse when the snapshot manager does not show all of the leftover snapshots, leaving the user/administrator with no GUI control over the situation.
