Administrator Guide

Keep these guidelines in mind when you name a consistency group:
• There is a minimum required capacity for a consistency group repository (depending on your configuration).
• When you define the capacity requirements for a repository, keep in mind any future requirements that you might have for other
virtual disks in this disk group or disk pool. Make sure that you have enough capacity to meet your data storage needs, but you do not
over allocate because you can quickly use up all the storage in your storage array.
• The list of repository candidates can contain both new and existing repository virtual disks. Existing repository virtual disks are left on
the storage array by default when you delete a consistency group. Existing repository virtual disks are placed at the top of the list. The
benefit to reusing an existing repository virtual disk is that you can avoid the initialization process that occurs when you create a new
one.
To create a consistency group repository:
1. From the AMW, select the Storage & Copy Services tab.
2. Select Copy Services→ Consistency Group→ Create.
The Consistency Group Settings window is displayed.
3. Select Manual and click Next to customize the repository candidate settings for the consistency group.
The Consistency Group Repository Settings - Manual window is displayed.
4. Select how you want to filter the repository candidates for each member virtual disk in the consistency group, based on either a
percentage of the base virtual disk capacity or by preferred capacity.
The best repository candidate for each member virtual disk based on the selections you made is displayed.
5. Select Edit individual repository candidates if you want to edit repository candidates for the member virtual disks.
6. Select the repository, from the Repository candidates table, that you want to use for each member virtual disk in the consistency
group.
NOTE: Select a repository candidate that is closest to the capacity you specified.
• The Repository candidates table shows both new and existing repositories that are capable of being used for each member
virtual disk in the consistency group based on the value you specified for percentage or the value you specified for preferred
capacity.
• By default, the system displays the repositories for each member virtual disk of the consistency group using a value of 20% of the
member virtual disk’s capacity. It filters out undersized repository candidates, and those with different Data Service (DS)
attributes. If appropriate candidates are not returned using these settings, you can click Run Auto-Choose to provide automatic
candidate recommendations.
• The Difference column shows the mathematical difference between your selected capacity and the actual capacity of the
repository candidate. If the repository candidate is new, the system uses the exact capacity size that you specified and displays
zero (0) in the Difference column.
7. To edit an individual repository candidate:
a. Select the candidate from the Repository candidates table and click Edit to modify the capacity settings for the repository.
b. Click OK.
8. Select View advanced options and then accept or change the following default settings as appropriate.
9. Click Finish.
Changing snapshot group settings
Use the Snapshot Group Change Settings option to modify the auto-delete settings and the snapshot group repository settings that
were configured when you created the snapshot group.
• Auto-Delete Settings — You can configure each snapshot group to keep the total number of snapshot images in the group at or
below a user-defined maximum. When this option is enabled, the system automatically deletes the oldest snapshot image in the group,
any time a new snapshot is created, to comply with the maximum number of snapshot images allowed for the group.
• Snapshot Group Repository Settings — You can define a maximum percentage for the snapshot group repository that determines
when a warning is triggered when the capacity of a snapshot group repository reaches the defined percentage. In addition, you can
specify which policy to use when the capacity of the snapshot group repository reaches its maximum defined percentage:
○ Automatically purge oldest snapshot image — The system automatically purges the oldest snapshot image in the snapshot
group, which releases the repository’s reserve space for reuse within the snapshot group.
• Reject writes to base virtual disk: When the repository reaches its maximum defined percentage, the system rejects any I/O write
request to the base virtual disk that triggered the repository access.
1. From the AMW, select the Storage & Copy Services tab.
2. From the snapshot groups category node, select the snapshot group that you want to change and then select Copy Services >
Snapshot Group > Change Settings.
The Change Snapshot Group Settings window is displayed.
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Premium feature—Snapshot Virtual Disk