Enabling the XRC enhanced multiple readers through the parmlib settings

Refer to the following scenarios to enable the XRC enhanced readers through the parmlib settings.

If there is only one SCSN for one SSID, specify the parameters for the XRC enhanced multiple reader in the parmlib. The SDM determines the conversion to enhanced multiple reader. There must be auxiliary storage control sessions for the SSID.

If there are multiple storage control session names for one SSID with XRCUTL volumes, enable the XRC enhanced readers according to the following steps:

  1. Issue an XADDPAIR command for the XRCUTL volume for one of the SCSESSIONs. The session is converted to the enhanced primary mode.
  2. Issue an XADDPAIR command for the new XRCUTL volume with the existing SCSESSION id.
  3. Specify the PARMLIB setting to indicate how many storage control sessions are used.
  4. Remove extraneous XRCUTL devices.

Here is an example for the multiple SCSNs scenario:

Specify 4 read tasks for the following combined SCSNs:

  1. Issue the following command: 
    XADD(UTC001, XRCUTL) SCSESSION(AA)
  2. Set the parmlib value to 4 and activate the value.

All the volumes in AA and BB on the LSS are in a single session using four reader tasks on volumes UTC000 and UTC001. Two additional volumes are added. You can remove the UTC001 device by issuing an XDELPAIR command.

If there are multiple SCSNs for one SSID without XRCUTL volumes, use the following steps to enable the enhanced multiple reader function:

  1. Add an XRCUTL volume to one of the extra SCSNs.
  2. Issue the following command: 
    XADD(newvol,XRCUTL) SCSESSION(SCSN id)
  3. Delete the XRCUTL volume from the primary SCSN.
    Note: To merge SCSNs into the primary volume, repeat step 1 to 3.
  4. Specify the PARMLIB setting and remove the extraneous XRCUTL volumes.

If there are no volumes available to use as an XRCUTL volume, temporarily stop mirroring at least one volume per LSS. For example, issue an XDELPAIR command, to delete an existing volume pair, to use the pair as the XRCUTL volume. When the XRC enhanced multiple reader starts, issue an XADDPAIR command to add the original volume pair back into the session. If applications are quiesced during the operation, and the original primary and secondary volumes are still synchronized, you can issue a NOCOPY command. If the primary volumes and secondary volumes are different, issue a full COPY command.

Parent topic: Enabling the XRC enhanced multiple reader function