Expanding DP-VOL capacity when TrueCopy pair is used with Thin Image Advanced

True Copy User Guide for VSP One Block

Version

10.4.x

Audience

anonymous

Part Number

MK-23VSP1B020-04

You can expand the capacity of DP-VOLs used as pair volumes when a TC pair is used with TIA. This procedure provides an example for expanding the DP-VOL capacity in a configuration where the TIA L1 pair and L2 pair are created for each volume of the P-VOL and S-VOL in the TC pair. For the detailed procedures for verifying the differential data management method, expanding the capacity, and verifying the expansion during the following procedure, see Expanding DP-VOL capacity used in TrueCopy pair .

A V-VOL to be expanded is not an external volume.
The LDEV format is not being performed on a V-VOL to be expanded.
A pool containing a V-VOL to be expanded meets any of the following conditions:
- Normal condition
- The pool is not being shrunk
When using GAD, TC, or UR, make sure that there is enough software license capacity for the page capacity assigned to the expanded volume capacity before the expansion.
A V-VOL to be expanded is created on a valid storage system. See Expanding DP-VOL capacity while keeping pair status.

See the VSP One Block Thin Image Advanced User Guide for details.

Verify that each volume of the P-VOLs and S-VOLs in a TC pair and TIA pairs with which the TC pair shares the same volumes meets the prerequisites.
Display the detailed information about the TC pair on CCI.
Verify whether the current differential data management method is the SM difference management or the hierarchical difference management by a drive.
- If the SM difference management is applied, proceed to step 3.
- If the hierarchical difference management is applied, proceed to step 4.
Change the differential data management method to the hierarchical difference management.
1. Change system settings for hierarchical difference management.
  If using CCI, set the system option mode (SOM) 1198 to ON and 1199 to OFF by using the raidcom modify system_opt command.
  Command example:
```
raidcom modify system_opt -system_option_mode system -mode_id 1198 -mode enable
```
```
raidcom modify system_opt -system_option_mode system -mode_id 1199 -mode disable
```
2. Suspend the TC pair.
3. Resynchronize the TC pair.
4. Display the detailed information about the TC pair on CCI, and then verify that the current differential data management method is the hierarchical difference management.
Suspend the TC pair.
Verify the pair statuses of the TIA pairs.
The TIA pair volume capacity can be expanded when the TIA pairs are in the PAIR, PSUS or PSUE status. Verify the current pair statuses of the TIA pairs. If the pair statuses are not PAIR, PSUS or PSUE, perform the pair operations, and then make sure that the pair statuses are migrated to PAIR or PSUS.
Expand each volume capacity, and then verify that the expansion is complete in the expansion order shown in the following figure.

After expanding the first volume capacity (S-VOL in the UR pair), if you cannot expand the DP-VOL capacity in the TIA pair, you cannot expand the P-VOL capacity in the TC pair, or resynchronizing the TC pair, make sure to perform the recovery procedure described in Recovering from failure if one volume capacity in TrueCopy pair cannot be expanded.
Resynchronize the TC pair.
Verify that both the pair statuses of the P-VOL and S-VOL in each pair of the TC pair have changed to PAIR.
In addition, verify that each volume capacity in the TC pair and TIA pair is not being expanded.
If the P column in the pairdisplay command output shows an N status, P-VOL or S-VOL capacity in the TC pair volume capacity is not expanding.

If the output shows an E status, P-VOL or S-VOL capacity in the TC pair is expanding. The status continues to show an E status until you perform a pairresync command and the command completes. After that, the status changes to N. In the TIA pair, the E status is displayed for 30 seconds or so after the expansion of the P-VOL and S-VOL capacity is complete. After that, the status changes to N.