Administering Data Volumes

VRW enables you to administer data volumes from any host in an RDS. You can perform the following volume administration tasks using VRW:

• Associating Volumes to a Replicated Data Set
• Resizing a Data Volume in a Replicated Data Set
• Dissociating a Data Volume from its Replicated Data Set

The VRW wizards that manage volume operations perform the operations on all RVGs in the RDS. The host from which the wizard is accessed is referred to as the local host. The name of the RVG on the local host represents the name of the RDS to which it belongs.

Associating Volumes to a Replicated Data Set

Use the Associate Volume wizard to associate one or more volumes to a Replicated Data Set (RDS) even when replication is in progress. This command associates the selected volumes to all the RVGs of the RDS. For each volume you are associating, ensure that volumes of the same name and same length exist on all the hosts in the RDS. You must create volumes of the required layout on the Primary and the Secondary.

Before associating volumes, the Associate Volume wizard displays a warning and prompts the user to confirm whether or not the Primary and Secondary volumes contain the same data. To verify that the Primary and Secondary volumes contain the same data, refer to the information provided in Verifying the Data on the Primary and Secondary Volumes. To synchronize the Primary and Secondary volumes, see Synchronizing Volumes on the Local Host and Remote Hosts.

Prerequisites for associating a volume to an RDS

  Create volumes of the same name and length as the Primary volume on all the hosts in the RDS.

  Verify that the volumes to be associated are inactive.

  Synchronize the volumes using the Synchronize Volume wizard.

  To associate a volume to an RDS

1. Select any view for the RDS for which the data volume is to be associated.
2. From the RDS or RVG view, choose Configuration > Associate Volume.
3. In the Volume Selection page, select the name of one or more data volumes to be associated to the RDS. To select multiple data volumes from the list, hold down the CTRL key and click the names of the required data volumes. To select a range of data volumes, select the first data volume in the range, hold down the SHIFT key, and then click the last name in the range. For example, hr_dv01 and hr_dv02.
4. Click Next.
5. In the confirmation page, check the box to indicate that the prerequisites have been met and click OK. If the operation is successful, a message displays to indicate that each data volume has been successfully associated to each corresponding RVG in the RDS.
6. In the status page, click Close. VRW updates and displays the RDS or RVG view from which you accessed the Associate Volume task.

Verifying the Data on the Primary and Secondary Volumes

The Verify Volume wizard enables you to verify whether there are any differences between remote volumes and the corresponding local volumes. You can use this command when the volumes are not associated with an RVG and the application is inactive (the volumes are not in use). The Verify Volume wizard only reports the amount of data that is different in percentage between remote and local volumes; it does not synchronize remote volumes with local volumes. VVR also allows you to verify the data volumes when replication is in progress. For more information on using the online data verification feature, refer to Verifying RVG Online.

This command can be useful to make sure that the data volumes are identical before adding them to an RDS.

Synchronizing Volumes on the Local Host and Remote Hosts

The Synchronize Volume wizard enables you to synchronize remote volumes with local volumes when the volumes are not associated with an RVG and the volumes are not in use. The data in the volumes on the local host, where you enter the command, is transferred over the network to the volumes on the remote host.

Use the Synchronize Volume wizard only to synchronize volumes that are not part of an RVG. For example, before adding a volume to an RDS, synchronize the volume using the Synchronize Volume wizard, and then add it to the RDS.

Using the Synchronize Volume wizard, you can synchronize remote volumes with local volumes using one of the following options:

• Difference-based synchronization
• Full synchronization

We recommend that the names of the volumes on the local and remote hosts be the same. However, you can synchronize volumes with different names on the local and remote hosts using the Synchronize Volume wizard.

Resizing a Data Volume in a Replicated Data Set

Use the Resize Volume task to resize a data volume in a Replicated Data Set (RDS) even when replication is in progress. The Resize Volume task resizes the specified data volume in all the RVGs in an RDS.

Important Notes for Resizing a Data Volume

• If the Primary data volume contains a file system, then resizing the data volume also resizes the file system.
• If replication to any Secondary RVG is in progress, resizing the volume pauses the Secondary, resizes the Primary data volume, and then resumes replication.
• If resizing the volume fails on any of the hosts in the RDS, original volume sizes are not restored. The volumes sizes won't match on the Primary and the corresponding Secondary hosts. To correct the mismatch, correct the error condition, run the Resize Volume wizard again to resize the volume, and resume replication.
• When you increase the size of a data volume, the newly added portions on the Primary and Secondary volumes are not synchronized.

Prerequisites for Resizing a Data Volume in an RDS

  The data volume must exist in the disk group and be associated with the RVGs for all hosts in the RDS.

  Make sure there is enough space in the disk group on the Primary and the Secondary to increase the size of a data volume.

  To resize a data volume in an RDS

1. Select any view for the RDS for which the data volume is to be resized.
2. From the RDS or RVG view, choose Configuration > Resize Volume.
3. View the Warnings page and click Next.
4. Complete the Resize Volume Options page as follows:

   Data Volume	Select the name of the data volume to be resized. For example, hr_dv01.
   Increase By	To increase the data volume by a specified size, select Increase By.
   Decrease By	To decrease the data volume by a specified size, select Decrease By.
   Resize To	To resize the data volume to a specified size, select Resize To. The default size unit is megabytes. To specify a size unit, select either sectors, kilobytes, or gigabytes from the drop-down list. Depending on the selected option, specify the size in the provided field.

5. Click OK to process the Resize Volume request.
6. Click Close in the status page of the Resize Volume wizard. VRW updates and displays the RDS or RVG view from which you accessed the Resize Volume task.

Dissociating a Data Volume from its Replicated Data Set

Perform the Dissociate Volume task to remove one or more data volumes from an RDS. The Dissociate Volume task only dissociates the data volumes from the RVGs in an RDS and does not delete them.

The Dissociate Volume task removes the specified data volumes from the RDS in either of the following conditions:

• When replication is in progress that is, the RLINKs are in the CONNECT state.
• When replication is stopped, that is, the RLINKs are detached. To stop replication, use Replication > Stop.

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  Note    If you want the data volumes on the Primary and the Secondary to be consistent after they are dissociated, stop the application and make sure that the RLINKs are up to date before dissociating a data volume from its RDS.

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To remove a data volume from its RDS even when the Primary RVG has not been stopped, select the Remove the data volume even if the Primary RVG has not been stopped option from the Dissociate Volume dialog box.

  To dissociate a data volume from its RDS

1. Select any view for the RDS for which the data volume is to be dissociated.
2. From the RDS or RVG view, choose Configuration > Dissociate Volume.
3. Complete the Volume Selection page as follows:

   Data Volume

   Select the name of the data volumes that you want to dissociate. To select multiple data volumes from the list, hold down the CTRL key and click the names of the required data volumes. To select a range of data volumes, select the first data volume in the range, hold down the SHIFT key, and then click the last name in the range. For example, hr_dv01 and hr_dv02. We recommend that the applications and the Primary RVG be stopped before dissociating any data volumes.

   Option: Dissociate the data volume even if the Primary RVG has not been stopped

   Click to dissociate the data volume even if the Primary RVG has not been stopped.

4. Click OK to dissociate the volume.
5. Click Close. VRW updates and displays the RDS or RVG view from which you accessed the Dissociate Volume task.