You should understand the relationship between the GAD status, pair status, and I/O mode to be informed about your GAD pairs.
The following table lists the GAD statuses and describes the relationship between the GAD status, pair status, and I/O mode. "N" indicates that pair status or I/O mode cannot be identified due to a failure in the storage system.
| GAD status | When to suspend | P-VOL | S-VOL | Volume that has the latest data | ||
|---|---|---|---|---|---|---|
| Pair status | I/O mode | Pair status | I/O mode | |||
| Simplex | Not applicable | SMPL | Not applicable | SMPL | Not applicable | Not applicable |
| Mirroring | Not applicable | INIT | Mirror(RL) | INIT | Block | P-VOL |
| Not applicable | COPY | Mirror(RL) | COPY | Block | P-VOL | |
| Mirrored | Not applicable | PAIR | Mirror(RL) | PAIR | Mirror(RL) | P-VOL and S-VOL |
| Quorum disk blocked or no quorum disk volume | Not applicable | PAIR | Mirror(RL) | PAIR | Mirror(RL) | P-VOL and S-VOL |
| Suspended | Pair operation | PSUS | Local | SSUS | Block | P-VOL |
| Failure | PSUE* | Local | PSUE | Block | P-VOL | |
| PSUE* | Local | SMPL | Not applicable | P-VOL | ||
| PSUE* | Local | N | N | P-VOL | ||
| Pair operation | PSUS | Block | SSWS | Local | S-VOL | |
| Failure | PSUE | Block | SSWS* | Local | S-VOL | |
| SMPL | Not applicable | SSWS* | Local | S-VOL | ||
| N | N | SSWS* | Local | S-VOL | ||
| Blocked | Not applicable | PSUE | Block | PSUE | Block | P-VOL and S-VOL |
| Not applicable | PSUE | Block | N | N | P-VOL and S-VOL | |
| Not applicable | N | N | PSUE | Block | P-VOL and S-VOL | |
|
*: If the server does not issue the write I/O, the pair status might be PAIR, depending on the failure location. |
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