How Thin Image Advanced pair status changes

The Thin Image Advanced pair status changes as you create or split the pair or perform other pair tasks.

The following figure shows the transition of pair statuses. You can view the pair status in CCI and HDvM - SN, but some of the statuses are displayed differently between in CCI and HDvM - SN. In this manual, such pair statuses are written as, for example, "COPY/COPY (PD)". Here the "COPY" is the status displayed in CCI, and "COPY (PD)" is the status displayed in HDvM - SN. For details about the correspondence of pair statuses between in CCI and HDvM - SN, see Thin Image Advanced pair status definitions.

The following workflow describes the Thin Image Advanced pair status changes:

1. You choose two volumes that are in SMPL status and are not in use as a Thin Image Advanced pair.
2. You create a pair.

   The pair status changes to "COPY/COPY(PD)" at first, and then to "PAIR" after the pair creation finishes.

   If the usage rate of the DP pool exceeds the depletion threshold when the pair is in "PAIR" status, the pair status displays "PFUL". When the usage rate of the DP pool exceeds the warning threshold, you cannot create a pair. When the pool is full, you cannot store snapshot data.

3. Snapshot data is stored when you split a pair in "PAIR" or "PFUL" status.

   While snapshot data is being stored, the pair status is "PSUP/PSUS(SP)". After snapshot data is stored, the pair status is "PSUS." Hosts cannot access the secondary volume while the pair status is "PSUP/PSUS(SP)".

   If the usage rate of the DP pool exceeds the depletion threshold when the pair is in "PSUS" status, the pair status displays "PFUS".

4. If you only want to delete snapshot data but do not want to release the Thin Image Advanced pair, you delete the snapshot data for the pair in "PSUS" or "PFUS" status (resynchronize the pair).

   While the snapshot data is being deleted, the pair is in "COPY/COPY(RS)" status. After the snapshot data is deleted, the pair status becomes "PAIR" or "PFUL".

5. If you restore a Thin Image Advanced pair in "PSUS" or "PFUS" status, snapshot data is overwritten to the primary volume.

   The pair status is "RCPY/COPY(RS-R)" when the restore process is in progress. The pair status is "PSUS" or "PFUS" after the restore process finishes. After the pair is restored, the snapshot data used for the restore operation will be maintained as the data as of the pair split. For example, after the pair restoration is normally performed and then the P-VOL is updated, you can use this snapshot as data to restore the same pair again.

6. If you assign the S-VOL, release the assignment of the S-VOL, or change the assigned volume to the Thin Image Advanced pair, the pair status is changed to "CPYP/COPY(SP)". After the operation finishes, the pair status is return to the status before the operation. When you change the S-VOL, two processing (assigning the volume and releasing the assignment) are carried out at the same time.
7. If you delete the Thin Image Advanced pair, the status of the pair is changed to "SMPP/SMPL(PD)". After the delete processing finishes, the pair status is changed to "SMPL".
8. If a failure occurs while the pair status is other than "SMPL" or "PSUE", the pair status is changed to "PSUE", and the snapshot data is lost.