6.5.1

Snapshots and Virtual Volumes
Snapshots preserve the state and data of a virtual machine at the time you take the snapshot. Snapshots
are useful when you must revert repeatedly to the same virtual machine state, but you do not want to
create multiple virtual machines. Virtual volumes snapshots serve many purposes. You can use them to
create a quiesced copy for backup or archival purposes, or to create a test and rollback environment for
applications. You can also use them to provision application images instantly.
In Virtual Volumes environment, snapshots are managed by ESXi and vCenter Server, but are performed
by the storage array.
Each snapshot creates an extra virtual volume object, snapshot, or memory, virtual volume, that holds the
contents of virtual machine memory. Original VM data is copied to this object, and it remains read-only,
which prevents the guest operating system from writing to snapshot. You cannot resize the snapshot
virtual volume. And it can be read only when the VM is reverted to a snapshot. Typically, when you
replicate the VM, its snapshot virtual volume is also replicated.
Read Only Read Write Read Only
Storage Container
Base VVolSnap-001VVol Snap-002 VVol
The base virtual volume remains active, or read-write. When another snapshot is created, it preserves the
new state and data of the virtual machine at the time you take the snapshot.
Deleting snapshots leaves the base virtual volume that represents the most current state of the virtual
machine. Snapshot virtual volumes are discarded. Unlike snapshots on the traditional datastores, virtual
volumes snapshots do not need to commit their contents to the base virtual volume.
Read Write
Storage Container
Base VVol
For information about creating and managing snapshots, see the vSphere Virtual Machine Administration
documentation.
Before You Enable Virtual Volumes
To work with Virtual Volumes, you must make sure that your storage and vSphere environment are set up
correctly.
vSphere Storage
VMware, Inc. 276