The SAN Volume Controller provides
support for the Microsoft® Volume
Shadow Copy Service and Virtual
Disk Service. The Microsoft Volume
Shadow Copy Service can provide a point-in-time (shadow) copy of a Windows® host volume while the
volume is mounted and files are in use. The Microsoft Virtual
Disk Service provides a single vendor and technology-neutral interface
for managing block storage virtualization, whether done by operating
system software, RAID storage hardware, or other storage virtualization
engines.
The following components are used to provide support for the service:
- SAN Volume Controller
- The cluster CIM server
- IBM® System Storage® hardware
provider,
known as the IBM System Storage Support for Microsoft Volume Shadow Copy
Service and Virtual Disk Service software
- Microsoft Volume Shadow
Copy Service
The
IBM System Storage hardware
provider is
installed on the Windows host.
To provide the point-in-time shadow copy, the components complete
the following process:
- A backup application on the Windows host
initiates a snapshot backup.
- The Volume Shadow Copy Service notifies the IBM System Storage hardware
provider that
a copy is needed.
- The SAN Volume Controller prepares
the volumes for a snapshot.
- The Volume Shadow Copy Service quiesces the software applications
that are writing data on the host and flushes file system buffers
to prepare for the copy.
- The SAN Volume Controller creates
the shadow copy using the FlashCopy® Copy
Service.
- The Volume Shadow Copy Service notifies the writing applications
that I/O operations can resume, and notifies the backup application
that the backup was successful.
The Volume Shadow Copy Service maintains a free pool of virtual
disks (VDisks) for use as a FlashCopy target
and a reserved pool of VDisks. These pools are implemented as virtual
host systems on the SAN Volume Controller.