Dell EqualLogic PS6210XS EqualLogic Group Manager Administrator s Guide PS Ser - Page 244

The secondary group administrator delegates space to the primary group when configuring the group as a replication partner. The administrator can modify the partner configuration and increase or decrease delegated space as needed. When the primary group administrator configures a volume for replication, a portion of that delegated space is reserved for the volume. This space, called replica reserve, limits the number of replicas for that volume that you can keep on the secondary group. You can modify the volume replication configuration and increase or decrease the replica reserve value as needed. (Note that replication borrowing can also affect the size of the reserve. See About Replication Borrowing for more information.) To determine the correct amount of space that the secondary group needs to delegate to the primary group, you must obtain the replica reserve requirement for each primary group volume that you are replicating to the secondary group. Replica reserve is based on a percentage of the volume's volume reserve. For more information, see Guidelines for Sizing Delegated Space. Manage Space Delegated to a Partner You can modify the space delegated to a partner, subject to the following restrictions: • You cannot decrease the space delegated to a lower capacity than is currently reserved for the partner's replicas. • The Pool Space table shows how pool space is currently used and how much space is used after the change. If more than one pool is configured to have delegated space, the first row of the table shows the overall statistics for delegated space usage across all pools. The lower rows show this information for the currently selected pool. If the new delegated space exceeds the capacity of a pool, the color of the table cell showing free pool space changes to red. For additional information, see Guidelines for Sizing Delegated Space. To modify the space delegated to a partner: 1. Click Replication and expand the replication partner. 2. Click Volume Replication. 3. In the Activities panel, click Manage delegated space to open the Manage Delegated Space dialog box. 4. Enter the new delegated space value. (If the group has more than one pool, you can specify a new value for each one as needed.) 5. Click OK. About Replica Reserve Usage To provide space for partner replicas, the secondary group delegates space to the partner. When you configure a volume for replication, you assign a portion of delegated space to the volume. This space, called replica reserve, limits the number and size of volume replicas that you can keep on the secondary group. It is important to correctly size the replica reserve for a volume. Too little replica reserve might prevent you from keeping the desired number of replicas. However, delegated space is limited, so keeping too many replicas might not be an efficient use of delegated space. When you configure a volume for replication, you specify the replica reserve size as a percentage (minimum 105 percent) of the replica volume reserve, which approximates in-use volume space. As volume usage increases, the replica reserve also increases, providing more space for replicas. For example, if you specify 200 percent for the replica reserve, and the replica volume reserve is 2.5GB, the replica reserve size is 5.0GB. If the replica volume reserve increases to 6.0GB, the replica reserve size increases to 12.0GB. The replica volume reserve has a maximum size (the reported volume size for volumes that are not thin-provisioned, or the maximum in-use space value for thin-provisioned volumes); therefore, the replica reserve has a maximum size. To properly size replica reserve, you must understand how replica reserve space is used. Replica Reserve Usage - First Replication 1. The primary group determines how much volume data to replicate. For the first replication operation, the primary group must copy all the volume data. 244 About Backing Up and Protecting Your Data