6.0.1

File Description
vmname-number.vmdk and vmname-
number-delta.vmdk
Snapshot file that represents the difference between the current state of the virtual
disk and the state that existed at the time the previous snapshot was taken.
The filename uses the following syntax, S1vm-000001.vmdk where S1vm is the
name of the virtual machine and the six-digit number, 000001, is based on the
files that already exist in the directory. The number does not consider the number
of disks that are attached to the virtual machine.
vmname.vmsd
Database of the virtual machine's snapshot information and the primary source of
information for the Snapshot Manager.
vmname.Snapshotnumber.vmsn
Memory state of the virtual machine at the time you take the snapshot. The file
name uses the following syntax, S1vm.snapshot1.vmsn, where S1vm is the
virtual machine name, and snapshot1 is the first snapshot.
NOTE A .vmsn file is created each time you take a snapshot, regardless of the
memory selection. A .vmsn file without memory is much smaller than one with
memory.
Snapshot Limitations
Snapshots can affect virtual machine performance and do not support some disk types or virtual machines
configured with bus sharing. Snapshots are useful as short-term solutions for capturing point-in-time virtual
machine states and are not appropriate for long-term virtual machine backups.
n
VMware does not support snapshots of raw disks, RDM physical mode disks, or guest operating
systems that use an iSCSI initiator in the guest.
n
Virtual machines with independent disks must be powered off before you take a snapshot. Snapshots of
powered-on or suspended virtual machines with independent disks are not supported.
n
Snapshots are not supported with PCI vSphere Direct Path I/O devices.
n
VMware does not support snapshots of virtual machines configured for bus sharing. If you require bus
sharing, consider running backup software in your guest operating system as an alternative solution. If
your virtual machine currently has snapshots that prevent you from configuring bus sharing, delete
(consolidate) the snapshots.
n
Snapshots provide a point-in-time image of the disk that backup solutions can use, but Snapshots are
not meant to be a robust method of backup and recovery. If the files containing a virtual machine are
lost, its snapshot files are also lost. Also, large numbers of snapshots are difficult to manage, consume
large amounts of disk space, and are not protected in the case of hardware failure.
n
Snapshots can negatively affect the performance of a virtual machine. Performance degradation is
based on how long the snapshot or snapshot tree is in place, the depth of the tree, and how much the
virtual machine and its guest operating system have changed from the time you took the snapshot.
Also, you might see a delay in the amount of time it takes the virtual machine to power-on. Do not run
production virtual machines from snapshots on a permanent basis.
n
If a virtual machine has virtual hard disks larger than 2TBs, snapshot operations can take significantly
longer to finish.
Managing Snapshots
You can review all snapshots for the active virtual machine and act on them by using the Snapshot Manager.
After you take a snapshot, you can use the Revert to Latest Snapshot command from the virtual machine’s
right-click menu to restore that snapshot at any time. If you have a series of snapshots, you can use the
Revert to command in the Snapshot Manager to restore any parent or child snapshot. Subsequent child
snapshots that you take from the restored snapshot create a branch in the snapshot tree. You can delete a
snapshot from the tree in the Snapshot Manager.
Chapter 10 Managing Virtual Machines
VMware, Inc. 195