HP ProLiant ML310 G3 Storage Server - Manual (Page 44)

Expanding storage for EVA arrays using Command View EVA
Presenting a virtual disk offers its storage to a host. To make a virtual disk available to a host, you must
present it. You can present a virtual disk to a host during or after virtual disk creation. The virtual disk
must be completely created before the host presentation can occur. If you choose host presentation
during virtual disk creation, the management agent cannot complete any other task until that virtual
disk is created and presented. Therefore, HP recommends that you wait until a virtual disk is created
before presenting it to a host.
For more information, see the HP StorageWorks Command View EVA User Guide.
Expanding storage using the Array Configuration Utility
The Array Configuration Utility enables online capacity expansion of the array and logical drive for
specific MSA storage arrays, such as the MSA1000 and MSA1500. For more information, use the ACU
online help, or the procedures to “Expand Array” in the Array Configuration Utility User Guide
Expand logical drive
This option in the ACU increases the storage capacity of a logical drive by adding unused space on an
array to the logical drive on the same array. The unused space is obtained either by expanding an array
or by deleting another logical drive on the same array. For more information, use the ACU online help, or
the “Extend logical drive” procedure in the Array Configuration Utility User Guide
Volume shadow copies
NOTE:
Select storage servers can be deployed in a clustered as well as a non-clustered configuration. This
chapter discusses using shadow copies in a non-clustered environment.
The Volume Shadow Copy Service provides an infrastructure for creating point-in-time snapshots (shadow
copies) of volumes. Shadow Copy supports 64 shadow copies per volume.
A shadow copy contains previous versions of the files or folders contained on a volume at a specific
point in time. While the shadow copy mechanism is managed at the server, previous versions of files
and folders are only available over the network from clients, and are seen on a per folder or file level,
and not as an entire volume.
The shadow copy feature uses data blocks. As changes are made to the file system, the Shadow Copy
Service copies the original blocks to a special cache file, to maintain a consistent view of the file at a
particular point in time. Because the snapshot only contains a subset of the original blocks, the cache
file is typically smaller than the original volume. In the snapshot's original form, it takes up no space
because blocks are not moved until an update to the disk occurs.
By using shadow copies, a storage server can maintain a set of previous versions of all files on the
selected volumes. End users access the file or folder by using a separate client add-on program, which
enables them to view the file in Windows Explorer. Accessing previous versions of files, or shadow
copies, enables users to:
• Recover files that were accidentally deleted. Previous versions can be opened and copied to
a safe location.
• Recover from accidentally overwriting a file. A previous version of that file can be accessed.
• Compare several versions of a file while working. Use previous versions to compare changes
between two versions of a file.
Shadow copies cannot replace the current backup, archive, or business recovery system, but they can
help to simplify restore procedures. Because a snapshot only contains a portion of the original data
blocks, shadow copies can not protect against data loss due to media failures. However, the strength
44 File server management