Deleting snapshot data
After writing data to a Thin Image pair volume, if the capacity of the snapshot data exceeds the pool capacity, the Thin Image pair changes to the PSUE status (indicating a failure occurred). In the PSUE status, the snapshot data is lost. Therefore, you cannot access the snapshot data. In this case, you cannot create a new Thin Image pair, and you must delete snapshot data which is no longer necessary. To delete snapshot data, perform either of the following methods:
- You must have the Storage Administrator (Local Copy) role.
- In CCI, use the raidcom modify snapshot -snapshot_data resync command.
- Deleting Thin Image pairs
Deleting Thin Image pairs deletes snapshot data stored in a pool and cancels the relationship between the P-VOL and the S-VOL.
- Deleting snapshot data only
To delete snapshot data only, use the Resync Pairs window in HDvM - SN, or the raidcom modify snapshot -snapshot_data resync command in CCI to delete snapshot data or restore Thin Image pairs. If you deleted only snapshot data, the relationship between the P-VOL and the S-VOL is maintained. If you delete only snapshot data, you can assign the MU numbers of the snapshot data you deleted when you store snapshot data of the Thin Image pair later. For details about the Resync Pairs window, see Restoring Thin Image pairs or Deleting Thin Image pairs.
When you delete snapshot data, the pair status changes to PAIR. Even if you update the primary volume from the host, the snapshot data is no longer stored. To resume storing snapshot data, split the Thin Image pair again.
The amount of time required for deleting snapshot data depends on the following, even if the pair synchronization ratio is 100 percent:
- The amount of pool capacity a pair is using.
- The number of pairs being operated concurrently.
The pair synchronization rate shows the rate that S-VOL data matches that of the next generation of the S-VOL. If the S-VOL is the latest one, the synchronization rate is computed by comparing the S-VOL with the P-VOL.
For the Thin Image pair where the cascade attribute is enabled, the information displayed in Synchronization Rate (%) of the View Pair Synchronization Rate window in HDvM - SN, or the raidcom get snapshot command in CCI varies depending on the pair status.