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# Create SRDF groups

SRDF groups provide a collective data transfer path linking volumes of two separate storage systems.

## About this task

To create an SRDF group:

## Steps

1. Select the storage system.
2. Select DATA PROTECTION > SRDF Groups and click Create SRDF Group, or select CREATE SRDF GROUP from the PROTECTION dashboard.
3. Select a Communication Protocol to use when moving data across the SRDF links.
   The value that you select here populates the Director Port list.
4. Select a Remote Array ID.
5. To refresh the remote storage system information, click Scan.
   The scan operation looks for SRDF capable systems that are known to Unisphere.
6. Type a SRDF Group Label (name).
7. Optional: Click SRDF/Metro Witness Group.
   This checkbox is selectable when the local storage system and the remote selected storage system are both Witness capable.
8. Select a local SRDF Group Number.
9. Select the local director ports through which the group communicates.
10. Click Advanced Options to set the advanced options, as described next.

    Setting Advanced options:

    1. Select a local Link Limbo Period. This period is a length of time for the storage system to continue checking the local SRDF link status. (The range is 0-120 s, default is 10.) If the link status is Not Ready after the link limbo time, the volumes are made Not Ready to the link.
    2. Select (enable) Local Link Domino for the local group. When this feature is enabled from either the local or remote side of group's SRDF links, failure of the group's last remaining link results in all source (R1) volumes in the group being unavailable (not ready) to their host when an R1-side operation occurs. This setting ensures that the data on the source (R1) and target (R2) devices is always in synch.
    3. Select (enable) Local Auto Link Recovery for the local group. When this feature is enabled, once the link failure is corrected, volumes that were ready to their host before the failure are automatically restored to the ready state.
    4. Click OK.
11. Select a Remote SRDF Group Number.
12. Select the remote director ports through which the group communicates.
13. Click Advanced Options to set the advanced options, as described next.

    Setting Advanced options:

    1. Select a Remote Link Limbo Period. This period is a length of time for the storage system to continue checking the remote SRDF link status. (The range is 0-120 s, default is 10.) If the link status is Not Ready after the link limbo time, the volumes are made Not Ready to the link.
    2. Select (enable) Remote Link Domino for the remote group. When this feature is enabled from either the local or remote side of group's SRDF links, failure of the group's last remaining link makes all source (R1) volumes in the group unavailable (not ready) to their host when an R1-side operation occurs. This setting ensures that the data on the source (R1) and target (R2) volumes is always in synch.
    3. Select (enable) Remote Auto Link Recovery for the remote group. When this feature is enabled, once the link failure is corrected, volumes that were ready to their host before the failure are automatically restored to the ready state.
    4. Click OK.
    5. A summary page, displaying all values and options that are selected, is displayed.
14. Optional: Set one or more of the following:
    - Select (enable) Software Compression for the local group. This setting enables SRDF software data compression for SRDF groups that are defined on GigE, or Fibre Channel. You can enable or disable software compression on the R2 side, however, the setting of hardware compression on the R1 side is what enables or disables the feature.
    - Select (enable) Hardware Compression for the local group. This setting enables SRDF hardware data compression on an SRDF group that is defined on a GigE director. You can enable or disable software compression on the R2 side, however, the setting of hardware compression on the R1 side is what enables or disables the feature. This feature is not supported on storage systems running HYPERMAX OS 5977.
15. Do one of the following:
    - Click Run Now to perform the operation now.
    - Expand Run Now and click Add to Job List to add this task to the job list, from which you can schedule or run the task at your convenience. For more information, see Schedule jobs and Preview jobs.