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Figure 71 Configuration of the Delta Resync Operation that utilizes Remote Command Devices
HP StorageWorks Mirror Unit Descriptors
To setup Raid Manager Configuration for 3DC architecture, “mirror unit descriptors” (MU#) are used to distinguish and manage an application device group among 3 data centers. A mirror unit descriptor (MU#) is a special index number available with all volumes that provides an individual designator for each copy of the volume. The mirror unit descriptor is provided in the Raid Manager Configuration files to indicate the nature of the copy.
A volume can be represented with seven mirror unit descriptors. Out of seven mirror unit descriptors, three MU#'s are for local replication copies using Business Copy, and are represented in the HP StorageWorks RAID Manager (RM) configuration file by the values 0, 1, and 2. The RM configuration file assumes MU# of 0 when no MU# is specified in the configuration file. However to avoid confusion, the 0 should be explicitly defined in the configuration for Business Copy.
The fourth MU# can be used for either Continuous Access Synchronous, or Continuous Access Asynchronous, or Journal. When it is used for Sync/Async, the MU# can be either 0 or left blank. The remaining three MU#'s are for Continuous Access Journal replication pairs only. These MU#'s are represented by h1, h2, and h3 values in the RM configuration file.
Figure 72 (page 422) shows all the available mirror unit descriptors for each data device, as well as the value to use in the HP StorageWorks RAID Manager (RM) configuration file to identify the specific replication instance for the device and any environment variables (for example, HORCC_MRCF) necessary to address the Business copy or Continuous Access using RAID Manager.
Overview of 3DC DR Solution 421