Reintroducing frozen system logger CDSs into your sysplex

Edit online

In the event that CDSs become frozen, you can correct the issue that resulted in the freeze and re-introduce the CDS into your sysplex.

Reintroducing CDSs after an unplanned swap

After a suspend event, the secondary disks are frozen and you cannot access the disks. To recover at the secondary site, you must make the disks accessible by using IBM® Copy Services Manager to initiate a recover. The Recover command performs the steps necessary to make the target available as the new primary site. Upon completion of this command, the session is in the Target Available state.

If the active Copy Services Manager server was located at Site 1, and the system the server was running on failed, you must use your standby server to recover. Issue the Takeover command, before initiating the Recover command.

When the session is in the Target Available state, the systems at Site 2 can be restarted using the Site 2 volumes.

Switching Disks Back to Site 1 After an Unplanned Failover to Site 2

To switch disks back to Site 1, see the information about switching from Site 2 to Site 1 in the following sections.

Reintroducing CDSs after a planned swap

Typically, you perform a planned switch from Site 1 to Site 2 for one of the following reasons:

The Site 1 disk is temporarily unavailable because of a disruptive disk maintenance action.
Site 1 is temporarily unavailable in its entirety because of a site maintenance activity.

In these situations, switch the disks to Site 2. When the Site 1 disk is available again, switch back to the Site 1 disk when you have the Site 2-to-Site 1 mirroring in full duplex.

Considerations for a Planned Metro Mirror Swap

When the system logger CDS is part of the Metro Mirror session and you plan to switch your primary disks from Site 1 to Site 2, you must complete the following tasks to release the allocation against the system logger CDS:

Switch to the system logger CDS that is not in the Metro Mirror session (that is, make the Site 2 alternate system logger CDS the new primary system logger CDS) by issuing the following command:
```
SETXCF COUPLE,TYPE=LOGR,PSWITCH
```
Make the Site 2 spare CDS the new alternate data set by issuing the following command:
```
SETXCF COUPLE,TYPE=LOGR,ACOUPLE=(spare cds in site 2)
```

When you switch back from Site 2 to Site 1, switch the Metro Mirror direction and then perform a CDS switch to return to the normal CDS configuration. After you switch the Metro Mirror session direction, perform the following actions to switch the CDS:

Make the primary at Site 1 the alternate by issuing the following command:
```
SETXCF COUPLE,TYPE=LOGR,ACOUPLE=(original primary cds in site 1) 
```
Make the original primary the primary again using the following command:
```
SETXCF COUPLE,TYPE=LOGR,PSWITCH  
```
Make the original alternate CDS at Site 2 the alternate again using the following command:
```
SETXCF COUPLE,TYPE=LOGR,ACOUPLE=(original alternate cds in site 2)  
```

Considerations for Planned HyperSwap

If you are using Copy Services Manager planned HyperSwap capability and you have your system logger CDSs mirrored, when swapping disks from Site 1 to Site 2, switch your CDS configuration to use only Site 2 CDSs before running the SWAP command to perform the disk swap. When swapping back to the Site 1 disks, use the normal CDS configuration after the HyperSwap has completed successfully.