Disk Storage exceeding physical setting

[bfry24]

 Several VMs have grown much larger than they should have been allowed to and we are approaching hard disk issues on the server storage.

What could be causing this?  The disks are Thin Provisioned.

[a_p_]

This could be caused by either something that's indeed writing data to the virtual disk, or existing snapshots.

Please check the virtual disks' file names, to find out whether snapshots exist, and do not just reply on the Snapshot Manager.
If there are files like <vmname>-00000x.vmdk, the VM has snapshots.

An alternative to checking for snapshots manually is RVTools.

In case of snapshots, please be careful with deleting them, because deleting a snapshots actually merges the data from the snapshot file into its parent virtual disk file. Depending on that data, thin provisioned disks may grow, so make sure that you have sufficient free disk space on the datastore!

André