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

TrueCopy® User Guide
Version
9.8.5
Audience
anonymous
Part Number
MK-98RD9022-16

You can expand the capacity of DP-VOLs used as pair volumes when a TC pair is used with HTI. This procedure provides an example for expanding the DP-VOL capacity in a configuration where the HTI 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 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 used capacity of the pool does not exceed the depletion threshold
    • 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.
  • A V-Vol to be expanded is not used in a pair with the clone attribute.
  • Ensure that the following numbers required after the expansion do not exceed the maximum number allowed on the storage system:
    • The snapshot estimated manageable capacity
    • The number of cache management devices
    • The subscription limit of the V-VOL capacity
  • If a TC pair is used with Thin Image Advanced, ensure that the following numbers do not exceed the maximum number allowed on the storage system:
    • Estimated Configurable in Pools window
    • Number of cache management devices

For information about calculating these numbers, see Calculating the snapshot estimated manageable capacity, the numbers of cache management devices, and the subscription limit of the V-VOL capacity.

  1. Verify that each volume of the P-VOLs and S-VOLs in a TC pair and HTI pairs with which the TC pair shares the same volumes meets the prerequisites.
  2. 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.
    • If using HDvM - SN, verify the advanced system settings No.5 and No.6.
      • If both the advanced system settings No.5 and No. 6 are set to Disable, the SM difference management is applied. Go to Step 3.
      • If either or both the advanced system settings No.5 and No.6 are set to Enable, the hierarchical difference management is applied. Go to Step 4.
  3. 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
      • If using HDvM - SN, set the advanced system settings No. 5 to Enable and No.6 to Disable in the Edit Advanced System Settings window.
    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.
  4. Suspend the TC pair.
  5. Verify the pair statuses of the HTI pairs.
    The HTI pair volume capacity can be expanded when the HTI pairs are in the PAIR, PSUS or PSUE status. Verify the current pair statuses of the HTI 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.
  6. 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 HTI 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.
  7. Resynchronize the TC pair.
  8. 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 HTI pair is not being expanded.

    The following table shows how the expansion process is displayed.

    Expansion status CCI HDvM - SN
    P column in the pairdisplay or raidcom get snapshot command Processing Status field in the Remote Replication or HTI pairs window
    Not being expanded N Blank
    Being expanded E* Expanding*
    * This status has been displayed after expanding the P-VOL or S-VOL capacity in the TC pair, and before performing the pair resync operation. After the resync operation is complete, the status is migrated to the Not being expanded status. In the HTI pair, the Being expanded status is displayed for a while (30 seconds or so) after the expansion of the P-VOL and S-VOL capacity is complete. After that, the status is migrated to the Not being expanded status.