If there are no I/Os issued to the failure location, the GAD pair might not be suspended and remain in the same status as before the failure. The following procedures assume that there are I/Os issued to the failure location.
The following table lists the pair status (in the upper row) and I/O mode (in the lower row) in phases 1 to 6 of a failure occurrence during data migration.
| Phase of failure occurrence | Volume | Source GAD pair | Temporary GAD pair created for migration | Target GAD pair | |||
|---|---|---|---|---|---|---|---|
| Before the failure | After the failure | Before the failure | After the failure | Before the failure | After the failure | ||
| 1. Creating a temporary GAD pair for migration | P-VOL | PAIR Mirror(RL) | No change | COPY Mirror(RL) | No change | ||
| S-VOL | PAIR Mirror(RL) | No change | COPY Block | No change | |||
| 2. Creating a target GAD pair | P-VOL | PAIR Mirror(RL) | No change | COPY Mirror(RL) | No change | COPY Mirror(RL) | PSUE Local |
| S-VOL | PAIR Mirror(RL) | No change | COPY Block | No change | COPY Block | PSUS Block | |
| 3. Suspending the source GAD pair (at the P-VOL) | P-VOL | PSUS Local | No change | COPY Mirror(RL) | No change* | COPY Mirror(RL) | PSUE Local |
| S-VOL | SSUS Block | No change | COPY Block | No change* | COPY Block | PSUE Block | |
| 4. The temporary GAD pair is migrated to PAIR | P-VOL | PSUS Local | No change | PAIR Mirror(RL) | No change | COPY Mirror(RL) | PSUE Local |
| S-VOL | SSUS Block | No change | PAIR Mirror(RL) | No change | COPY Block | PSUE Block | |
| 5. Suspending the temporary GAD pair (at the S-VOL) | P-VOL | PSUS Local | No change | PSUS Block | No change | COPY Mirror(RL) | PSUE Local |
| S-VOL | SSUS Block | No change | SSWS Local | No change | COPY Block | PSUE Block | |
| 6. The target GAD pair is migrated to PAIR | P-VOL | PSUS Local | No change | PSUS Block | No change | PAIR Mirror(RL) | PSUE Local |
| S-VOL | SSUS Block | No change | SSWS Local | No change | PAIR Mirror(RL) | PSUE Block | |
| * The pair status and the I/O mode might be PAIR(Mirror(RL)) depending on the progress of copy operation. | |||||||