Planned and unplanned swaps
After a FlashSystem/IBM Spectrum Accelerate or z/OS session is enabled for HyperSwap, Copy Services Manager will set up HyperSwap relationships on the storage system. When the relationships are created and in a Prepared state, a planned or unplanned HyperSwap can occur.
When they are enabled, the session can start a planned or unplanned swap. A HyperSwap® symbol is displayed over the arrow that shows replication between sites, as shown in Figure 1.
TVT Instructions: This graphic was updated for Copy Services Manager 6.2.1, swapcapable.jpg. To capture this graphic from the Copy Services Manager GUI, the Copy Services Manager server must be on or attached to a z/OS host. Click Sessions > Click Create Session > In the Create Session window, select DS8000 or ESS in the Choose Hardware Type list > In the Choose Session Type list, select Basic HyperSwap. This graphic is also in the file frg_c_ct_metro_mirror_v2.dita.
Completing a planned swap
When the session is enabled on z/OS or FlashSystem/IBM Spectrum Accelerate for HyperSwap, the session is considered swap-capable. There might be cases such as a planned maintenance or a migration from the primary storage, in which a planned swap might be required. When the session is in swap-capable state, a planned swap can be completed by issuing the HyperSwap command for the session.
After you run a planned swap for z/OS, the session transitions to Target Available state and all the H1-H2 pairs are in Target Available state. If the H1-H2 role pair was consistent at the time of the swap, the session has a status of Normal, which indicates that H1-H2 is consistent. If the H1-H2 role pair was not consistent at the time of the swap, the session has a status of SEVERE. The active host on the session is shown as H2.
After a planned swap for FlashSystem/IBM Spectrum Accelerate, the session does not go into a Target Available state. The FlashSystem/IBM Spectrum Accelerate automatically reverses the replication so that the session goes Prepared in the opposite direction if the auto restart is successful, or it goes Target Available if it is not successful.
All I/O is redirected to the H2 volumes. After a successful swap to site 2, you cannot enable the copy function to site 2. The only way to restart the copy processing is by issuing the Start H2->H1 command. To have the volumes protected with high availability and disaster recovery again, correct the error that caused the swap to occur, and manually restart the session to begin copying data to the other site.
Unplanned swaps
When the session is enabled on z/OS or FlashSystem/IBM Spectrum Accelerate for HyperSwap processing, the session is considered swap-capable. If a primary I/O error occurs, a swap occurs automatically.
When an unplanned swap occurs for z/OS, the session transitions to Target Available state and all the H1-H2 pairs are in Target Available state. If the H1-H2 role pair was consistent at the time of the swap, the session has a status of Normal, and indicates that H1-H2 is consistent. If the H1-H2 role pair was not consistent at the time of the swap, the session might show a status of SEVERE. The active host on the session is shown as H2.
An unplanned swap on FlashSystem/IBM Spectrum Accelerate, most likely results in Target Available state. Because there is a primary I/O error in this situation, it probably means that the replication will not automatically start back in the opposite direction either.
All I/O is redirected to the H2 volumes. After a successful swap to site 2, you cannot enable the copy function to site 2. Therefore, it is not possible to issue a Start H1->H2 command. The only way to restart the copy processing is by issuing a Start H2->H1 command. To have the volumes protected with high availability and disaster recovery again, correct the error that caused the swap to occur, and manually restart the session to begin copying data to the other site.