6.7

Deleting a snapshot does not change the virtual machine or other snapshots. Deleting a snapshot
consolidates the changes between snapshots and previous disk states and writes all the data from the
delta disk that contains the information about the deleted snapshot to the parent disk. When you delete
the base parent snapshot, all changes merge with the base virtual machine disk.
To delete a snapshot, a large amount of information needs to be read and written to a disk. This process
can reduce virtual machine performance until consolidation is complete. Consolidating snapshots
removes redundant disks, which improves virtual machine performance and saves storage space. The
time it takes to delete snapshots and consolidate the snapshot files depends on the amount of data that
the guest operating system writes to the virtual disks after you take the last snapshot. The required time is
proportional to the amount of data the virtual machine is writing during consolidation if the virtual machine
is powered on.
Failure of disk consolidation can reduce the performance of virtual machines. You can check whether any
virtual machines require separate consolidation operations by viewing a list. For information about
locating and viewing the consolidation state of multiple virtual machines and running a separate
consolidation operation, see vSphere Virtual Machine Administration.
Delete Use the Delete option to remove a single parent or child snapshot from the
snapshot tree. Delete writes disk changes that occur between the state of
the snapshot and the previous disk state to the parent snapshot.
You can also use the Delete option to remove a corrupt snapshot and its
files from an abandoned branch of the snapshot tree without merging them
with the parent snapshot.
Delete All Use the Delete All option to delete all snapshots from the Snapshot
Manager. Delete all consolidates and writes the changes that occur
between snapshots and the previous delta disk states to the base parent
disk and merges them with the base virtual machine disk.
To prevent snapshot files from merging with the parent snapshot if, for example, an update or installation
fails, first use the Restore command to restore to a previous snapshot. This action invalidates the
snapshot delta disks and deletes the memory file. You can then use the Delete option to remove the
snapshot and any associated files.
Caution Use care when you delete snapshots. You cannot restore a deleted snapshot. For example,
you might want to install several browsers, a, b, and c, and capture the virtual machine state after you
install each browser. The first, or base snapshot, captures the virtual machine with browser a and the
second snapshot captures browser b. If you restore the base snapshot that includes browser a and take a
third snapshot to capture browser c and delete the snapshot that contains browser b, you cannot return to
the virtual machine state that includes browser b.
Prerequisites
n
Ensure that you are familiar with the Delete and Delete all actions and how they might affect virtual
machine performance.
vSphere Virtual Machine Administration
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