Expanding the capacity of a DP-VOL used in TrueCopy pair

When deciding to expand the capacity of a DP-VOL used as a volume in a TC pair, understand that there are two different procedures, each depending on whether the TC pair shares the same volumes with other software or does not share the same volumes. This procedure describes expanding DP-VOL capacity when the TC pair does not share the volume (a TC pair alone).

Ensure that the following conditions are met:

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
A V-VOL to be expanded is a volume created on the storage systems described in Expansion of DP-VOL capacity while keeping pair status
Make sure that there is enough TC license capacity for the page capacity assigned to the expanded volume capacity before the expansion

Note: Only the assigned page capacity out of the DP-VOL capacity is counted as the TC license capacity.

Verify that both the P-VOL and S-VOL of a TC pair meet the prerequisites.

Display the detailed information about the TC pair on CCI.

Verify whether the current differential data management method is the Shared memory (SM) difference management or the hierarchical difference management by a drive. The DM column displayed by the pairdisplay command shows whether the shared memory (S) difference management is applied or the hierarchical (D) difference management is applied.

# pairdisplay -g oradb -fe -fcx
Group PairVol L/R Port# TID LU Seq# LDEV# P/S Status Fence % PLDEV# M CTG JID AP EM E-Seq# E-LDEV# R/W QM DM P PR CS D_Status ST ELV PGID CT(s) LUT
oradb dev1 L CL5-A-0 30 0 64568 301 P-VOL PAIR NEVER 100 303 - - - 1 - - - -/- - S N - 3 - 02 - 0 0 2023-11-02T19:42:15
oradb dev1 R CL5-A-0 30 2 64568 303 S-VOL PAIR NEVER 100 301 - - - - - - - -/- - S N - 3 - 02 - 0 - 2023-11-02T19:42:01
oradb dev2 L CL5-A-0 30 1 64568 302 P-VOL PAIR NEVER 100 304 - - - 1 - - - -/- - D N - 3 - 02 - 0 0 2023-11-02T19:42:15
oradb dev2 R CL1-A-0 30 3 64568 304 S-VOL PAIR NEVER 100 302 - - - - - - - -/- - D N - 3 - 02 - 0 - 2023-11-02T19:42:01
# pairdisplay -g oradb -fe -fcx
Group PairVol L/R Port# TID  LU  Seq# LDEV# P/S Status Fence    % P-LDEV# M CTG JID AP EM       E-Seq# E-LDEV# R/W QM DM P
oradb dev1 L CL5-A-0 30 0 64568 301 P-VOL PAIR NEVER 100 303 - - - 1 - - - -/- - S N
oradb dev1 R CL5-A-0 30 2 64568 303 S-VOL PAIR NEVER 100 301 - - - - - - - -/- - S N
oradb dev2 L CL5-A-0 30 1 64568 302 P-VOL PAIR NEVER 100 304 - - - 1 - - - -/- - D N
oradb dev2 R CL1-A-0 30 3 64568 304 S-VOL PAIR NEVER 100 302 - - - - - - - -/- - D N

If the SM difference management is applied, go to Step 3 to temporarily change to hierarchical difference management.
If the hierarchical difference management is applied, go to Step 4.

Change the differential data management method to the hierarchical difference management.
1. Change system settings for hierarchical difference management.
  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.
  Verify that the current differential data management method is the hierarchical difference management.
Suspend the TC pair.
Expand the S-VOL capacity in the TC pair.
Using CCI, add -request_id auto option to the raidcom extend ldev command to specify the asynchronous command processing.
Command example

The following command expands the capacity of LDEV#44:44 by 10 GB.
```
raidcom extend ldev -ldev_id 0x4444 -capacity 10G –request_id auto -IH1
```
Note: A maximum of 65,280 request IDs can be assigned to one storage system. If there is no available request ID, the command fails with EX_IDEXHA. If that occurs, see the description of the function of request IDs in the Command Control Interface Command Reference and release request IDs.
Verify that expanding the S-VOL capacity in the TC pair is finished.
Using CCI, raidcom get command_status command to verify that the raidcom extend ldev command is finished processing.
Command example
```
raidcom get command_status -request_id <request#> -IH1
raidcom get ldev -ldev_id 0x4444 -fx -IH1
```
Verify the expanded LDEV capacity using the raidcom get ldev command.

Replace <request#> with the request ID that is displayed in step 5.
Confirm that asynchronous command processing has completed. Then release a request ID.
Command example
```
raidcom reset command_status -request_id <request#> -IH1
```
Expand the P-VOL capacity in the TC pair in the same way as the S-VOL capacity.
If the P-VOL capacity in the TC pair cannot be expanded, see Recovering from failure if one volume capacity in TC pair cannot be expanded.
Verify that expanding the P-VOL capacity in the TC pair is complete in the same way as the S-VOL capacity.
Resynchronize the TC pair.
If the resync operation in the TC pair cannot be performed, see Recovering from failure if one volume capacity in TC pair cannot be expanded.

Verify that the pair statuses of both the P-VOL and S-VOL in the TC pair have changed to PAIR, and that the volume capacity is not being expanded.

Using CCI, check that the P column of the pairdisplay command displays N.

# pairdisplay -g oradb -fe -fcx
Group PairVol L/R Port# TID LU Seq# LDEV# P/S Status Fence % PLDEV# M CTG JID AP EM E-Seq# E-LDEV# R/W QM DM P PR CS D_Status ST ELV PGID CT(s) LUT
oradb dev1 L CL5-A-0 30 0 64568 301 P-VOL PAIR NEVER 100 303 - - - 1 - - - -/- - S N - 3 - 02 - 0 0 2023-11-02T19:42:15
oradb dev1 R CL5-A-0 30 2 64568 303 S-VOL PAIR NEVER 100 301 - - - - - - - -/- - S N - 3 - 02 - 0 - 2023-11-02T19:42:01
oradb dev2 L CL5-A-0 30 1 64568 302 P-VOL PAIR NEVER 100 304 - - - 1 - - - -/- - D N - 3 - 02 - 0 0 2023-11-02T19:42:15
oradb dev2 R CL1-A-0 30 3 64568 304 S-VOL PAIR NEVER 100 302 - - - - - - - -/- - D N - 3 - 02 - 0 - 2023-11-02T19:42:01

# pairdisplay -g oradb -fe -fcx
Group PairVol L/R Port# TID  LU  Seq# LDEV# P/S Status Fence    % P-LDEV# M CTG JID AP EM       E-Seq# E-LDEV# R/W QM DM P
oradb dev1 L CL5-A-0 30 0 64568 301 P-VOL PAIR NEVER 100 303 - - - 1 - - - -/- - S N
oradb dev1 R CL5-A-0 30 2 64568 303 S-VOL PAIR NEVER 100 301 - - - - - - - -/- - S N
oradb dev2 L CL5-A-0 30 1 64568 302 P-VOL PAIR NEVER 100 304 - - - 1 - - - -/- - D N
oradb dev2 R CL1-A-0 30 3 64568 304 S-VOL PAIR NEVER 100 302 - - - - - - - -/- - D N

The P column in the pairdisplay command displays the status that the volume capacity is being expanded. An N indicates that the volume capacity is not being expanded, an E indicates that the volume capacity is being expanded.

The E status is displayed after expanding the P-VOL or S-VOL capacity in the TC pair, and before performing the pair resync operation. This status changes to N after the resync operation completes.