HP SAN Virtualization Services Platform - Manual (Page 60)

4 Creating a PiT and snapshot with Microsoft VSS
Microsoft VSS (Volume Shadow Copy Service), also known as Virtual Shadow Copy, is a unified
storage management interface for Microsoft Windows Server 2003 SP1 and later. Microsoft VSS
is intended primarily for a backup solution.
Figure 3 (page 60) shows the Microsoft VSS components
and their functions.
Figure 3 VSS components
Table 2 VSS component functions
Description Component
A service that coordinates various components to create consistent shadow copies
of one or more volumes. Volume Shadow Copy Service
An application that requests that a volume shadow copy be taken. A backup
application is an example. Requestor
A component of an application that stores persistent information on one or more
volumes that participates in shadow copy synchronization. Typically, this database
application is like SQL Server or Exchange Server or a system service like Active
Directory. Writer
A component that creates and maintains the shadow copies. Examples are the
hardware providers included with storage arrays. HP also provides a VSS hardware
provider for VSM. Provider
The volume that contains the data to be shadow copied. Source volume
The major benefit of using Microsoft VSS for backups or creating snapshots is the capability of
VSS to commit/flash (also known as “quiescing”) all I/O to the disks before taking the snapshots
receiving persistent data. There is no need to use the VSM CLI because the SVSP VSS hardware
provider is replacing the VSM CLI.
SVSP VSS Hardware Provider
The SVSP VSS Hardware Provider installs as a service on a Windows host and receives requests
from the VSS service on the host to create or delete snapshots. The SVSP VSS hardware then
communicates with the DPM and VSM to create or delete the snapshots by issuing requests to
create a PiT and then a snapshot, or delete the snapshot and then the PiT. After they are created,
the snapshots are also automatically assigned to the server from which the VSS request came.
For more information about how to install and configure the SVSP VSS Hardware Provider, refer
to the HP StorageWorks SAN Virtualization Services Platform Administrator Guide.
Using the Microsoft VSS to create a persistent PiT and snapshot
While the purpose of Microsoft VSS is to create persistent snapshots for backups, the Microsoft
VSS can also be used to create persistent snapshots for other uses, or to create a persistent user
PiT for a source virtual disk in an asynchronous mirror group.
60 Creating a PiT and snapshot with Microsoft VSS