Administrator Guide

• Select An existing snapshot image and then select a snapshot image from the consistency group snapshot images table and
click Next.
• Select A new snapshot image and then a snapshot group from the existing snapshot group table and then click Next.
The Consistency Group Snapshot Virtual Disk Settings window is displayed.
4. In the Consistency group snapshot virtual disk name field, enter a unique name (30 character maximum) that best describes the
consistency group selected for this snapshot image. For example, AccountingData.
By default, the consistency group snapshot virtual disk name is shown in the name text box as:[consistency-group-name] -
SV + sequence-number where SV (snapshot virtual disk) is the appended suffix and sequence-number is the chronological
number of the snapshot virtual disk relative to the consistency group.
For example, if you create the first snapshot virtual disk for a consistency group called “Accounting”, then the default name of the
snapshot virtual disk is “Accounting_SV_01”. The default name of the next snapshot virtual disk you create based on “Accounting” is
“Accounting_SV_02”.
There is a 30-character limit. After you reach this limit, you can no longer type in the text box. If the consistency group name is 30
characters, then the default name for the group uses the base virtual disk name truncated enough to add the suffix “SV” and the
sequence string.
5. In the Map to host drop-down, specify how you want to map the host for each snapshot virtual disk created for a selected member
virtual disk.
This map attribute is applied to every member virtual disk you select in the consistency group.
The following guidelines apply:
• Each host has its own logical unit number (LUN) address space and let the same LUN be used by different host groups or hosts to
access snapshot virtual disks in a storage array.
• You can define one mapping for each snapshot virtual disk in the storage array.
• Mappings are shared between RAID controller modules in the storage array.
• The same LUN cannot be used twice by a host group or a host to access a snapshot virtual disk. You must use a unique LUN.
• An access virtual disk mapping is not required for out-of-band storage arrays.
6. Select how to grant host access to each selected member virtual disk’s snapshot virtual disk. Do one of the following:
• Select Read/Write to provide the host application with WRITE access to a copy of the data contained in the snapshot image. A
Read-Write snapshot virtual disk requires an associated repository.
• Select Read Only to provide a host application with READ access to a copy of the data contained in the snapshot image, but
without the ability to modify the snapshot image. A Read-Only snapshot virtual disk does not have an associated repository.
7. Select each member virtual disk in the consistency group for which you want to create a snapshot virtual disk.
You can click Select all to create a snapshot virtual disk for each member virtual disk displayed in the select members table.
8. If you selected Read-Only host access in step 6, you can skip this step and go to step 9.
NOTE: Repositories are not required for Read-Only snapshot virtual disks.
9. Select how you want to create the snapshot virtual disk repositories for each member in the consistency group. Do one of the
following:
• Select Automatic and click Finish to create each snapshot virtual disk repository with the default capacity settings. This option is
the recommended one.
• Select Manual and click Next to define the properties for each snapshot virtual disk repository; then click Finish to continue with
the snapshot virtual disk creation process. You can click Edit individual repository candidates to manually edit a repository
candidate for each member virtual disk.
Use this option if you want to specify all the customizable settings for the snapshot virtual disk repository. The Manual method is
considered advanced and only those who understand physical disk consistency and optimal physical disk configurations should use this
method.
The snapshot virtual disk and its properties for the associated consistency group are displayed in the navigation tree.
Manually creating a consistency group Snapshot Virtual
Disk repository
During the creation of a consistency group snapshot virtual disk that is designated as read-write, the system requires a snapshot virtual
disk repository for each member of the consistency group to provide the host application with WRITE access to a copy of the data
contained in the snapshot image. You can create the repository automatically using the default settings or you can manually create the
repository by defining the capacity settings for the repository.
Premium feature—Snapshot Virtual Disk
119