Creating a Replicated Data Set

To create a Replicated Data Set (RDS) using VRW, perform the following tasks in the order listed below:

• Creating a Primary RVG of the RDS
• Adding a Secondary to the RDS

Creating a Primary RVG of the RDS

The first step in creating an RDS is creating its Primary RVG. VRW enables you to create a Primary RVG of an RDS using the Create Primary wizard. The Create Primary wizard enables you to associate existing data volumes and the Storage Replicator Log (SRL) with the Primary RVG. The Create Primary wizard performs the following operations:

• Creates the Primary RVG on the host to which you are connected; that is, the host to which you logged on or which you selected from the drop-down host list.
• Associates the specified data volumes and SRL with the RVG.
• Associates Data Change Maps (DCMs) to the data volumes in the RVG.
• Enables the Primary RVG by starting it.

To add more volumes after creating the RVG, use the Associate Volume wizard.

Prerequisites for creating a Primary RVG

  The data volumes and the SRL must exist in a disk group on the Primary host.

  All the data volumes used by the application MUST be in the same RVG.

  The data volumes and the SRL must be started.

  All the data volumes to be replicated and the SRL must be the same type. They must be all VxVM ISP volumes or VxVM non-ISP volumes.

For instructions on creating the data volumes and SRL, refer to the example in the VERITAS Volume Replicator Administrator's Guide.

  To create a Primary RVG of an RDS

1. From any view, choose Configuration > Create Primary.
2. Select the volume type. If the data volumes to be replicated were created using Intelligent Storage Provisioning, select the checkbox The volumes are VxVM ISP volumes.
3. Complete the RVG Name and Disk Group page as follows:

   RVG (RDS) Name	Enter a name for the Primary RVG. For example, hr_rvg.
   Disk Group	From the drop-down list, select the name of the disk group, that is, the disk group that contains the SRL and the data volumes to be associated with the Primary RVG. For example, hrdg. Note    If the checkbox The volumes are VxVM ISP volumes was selected on the previous page, the list only displays disk groups that contain VxVM ISP data volumes.

4. Click Next.
5. Complete the SRL and Data Volume page as follows:

   Replication Log

   From the drop-down list, select the volume that is to be configured as the SRL. For example, hr_srl. The SRL size must be at least 110MB.

   Data Volumes

   From the list, select the data volumes to be associated with the RVG. All of the data volumes used by the application MUST be included in the same RVG. 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. Note    If the checkbox The volumes are VxVM ISP volumes was selected on the first page, the list only displays VxVM ISP data volumes.

6. Click OK to proceed with the creation of the Primary RVG.
   • To make any changes to the RVG name or to select a different disk group, click Back.
   • To exit the Create Primary wizard and cancel the Create Primary operation, click Cancel.

   After the Primary RVG is created, the following message displays in a window:

   The Primary RVG is created on seattle.

7. Click Close. The Primary RVG view displays the newly created Primary RVG.

Adding a Secondary to the RDS

To add a Secondary RVG to the RDS, use the Add Secondary wizard from any host that is already a part of the RDS. The Add Secondary wizard also enables you to set up or change the replication settings between a Primary RVG and the Secondary that is being added. You can change the following replication settings for the Secondary:

• Mode of replication
• Latency protection
• SRL protection

Each setting affects performance and must be set up with care. For details on setting up mode of replication, latency protection and SRL protection, see the VERITAS Volume Replicator Administrator's Guide.

The host to which you are connected is referred to as the local host, and the name of the RVG on the local host is referred to as the local RVG. The local RVG represents the RDS to which it belongs, and the RDS is referred by its local RVG name.

When adding the Secondary, the Add Secondary wizard performs the following operations:

• Creates and adds a Secondary RVG with the same name as the Primary RVG, to the specified RDS on the Secondary host. By default, the Secondary RVG is added to the disk group with the same name as the Primary disk group. You can specify a different disk group by using the options provided in the second step of the Add Secondary wizard.
• Automatically adds DCMs to the Primary and Secondary data volumes if they do not have DCMs. If any of the data volumes or the SRL on the Secondary has a DRL, the DRL is removed before the data volume or SRL is associated with the RVG.
• Associates to the Secondary RVG existing data volumes of the same names and sizes as the Primary data volumes; it also associates an existing volume with the same name as the Primary SRL, as the Secondary SRL.
• Creates and associates Primary and Secondary RLINKs with default RLINK names rlk_remotehost_rvgname. The wizard enables you to specify different names for the Primary and Secondary RLINKs.

Prerequisites for adding a Secondary

Before creating and adding the Secondary RVG to the specified RDS, do the following:

  The Secondary data volumes and the SRL must be in the same disk group on the Secondary. Use a disk group with the same name as the Primary disk group, if possible.

  Create data volumes with the same names and sizes as the Primary data volumes.

  Create an SRL with the same name and size as the Primary SRL.

  Make sure the /etc/vx/vras/.rdg file contains the Primary disk group ID. For details, see the VERITAS Volume Replicator Administrator's Guide.

To display the Primary disk group ID, log on to the Primary host and issue the following command:


  # vxprint -l diskgroup

  To add a Secondary to an RDS

1. From the Summary view, the RDS view, or the RVG view, click the name of the RDS to which you want to add the Secondary RVG, and then choose Configuration > Add Secondary.
2. Complete the Primary and Secondary Host Names page as follows, and then click Next:

   Primary Host	Enter a host name or specify the IP address that is to be used for replication. The Primary host name must be resolvable and reachable from the Secondary host. For example, seattle. If you entered the IP address, it must be reachable from the Secondary host.
   Secondary Host	Enter a host name or specify the IP address that can be used for replication. The Secondary host name must be resolvable and reachable from the Primary host. For example, london. If you entered the IP address, it must be reachable from the Primary host.

3. In the RLINKs and Secondary Disk Group Names page, the default values for the Primary RLINK, Secondary RLINK, and the Secondary Disk Group display.

   If required, change the values for the Primary RLINK, Secondary RLINK, and the Secondary Disk Group by completing the RLINKs and Secondary Disk Group Names page as follows, or go to the next step:

   Primary RLINK	Enter another Primary RLINK name if the default name is not appropriate.
   Secondary RLINK	Enter another Secondary RLINK name if the default name is not appropriate.
   Secondary Disk Group	By default, the Secondary Disk Group box displays the name of the Primary disk group. This will be used as the name of the disk group on the Secondary that is to contain the Secondary RVG. If the default name is not appropriate, enter another Secondary disk group name. This disk group must contain the SRL and data volumes that are to be associated with the Secondary RVG that is being created.

4. Click Next.
5. In the Replication Settings page, the default values for Replication Mode, SRL Protection, and Latency Protection display.

   For information about replication settings, refer to the VERITAS Volume Replicator Administrator's Guide.

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     Note    After the Secondary has been successfully added, additional replication settings such as packet size, protocol, and bandwidth limit can be changed as described in Changing the Replication Settings.

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   To change the replication settings, complete the Replication Settings page as follows, or go to the next step.

   Replication Mode Asynchronous, Synchronous-Override	Asynchronous is selected by default. From the drop-down list, select the required mode of replication. To set the replication to synchronous mode, select Synchronous-Override.
   SRL Protection autodcm, dcm, off, override	By default, SRL protection is set to autodcm. From the drop-down list, select the required value to change the SRL protection mode. To enable SRL protection, select autodcm, dcm, or override. To disable SRL protection, select off. If you disable SRL protection, the SRL is allowed to overflow.
   Latency Protection override, off	By default, latency protection is set to override. To enable latency protection and limit the number of updates by which the Secondary is allowed to fall behind, select override. If you select override, the wizard displays the boxes Latency Low Mark and Latency High Mark with default values of 9950 and 10000 respectively. To disable latency protection, select off. To set the latency protection to fail, use the command-line interface (CLI). For details on selecting the appropriate option and using the CLI, refer to the VERITAS Volume Replicator Administrator's Guide.
   If Latency Protection is set to override:
   Latency High Mark	Displays only if Latency Protection is set to override. The default is 10000. Enter the required numerical limit.
   Latency Low Mark	Displays only if Latency Protection is set to override. The default is 9950. Enter the required numerical limit.

   If you select override in the Latency Protection box, the page looks like this:

   

   Click the thumbnail above to view full-sized image.

6. Click Finish. The Summary page displays the replication settings for the Secondary RVG.
7. Click OK to create the Secondary RVG. To make any changes, click Back.

   The Add Secondary operation succeeds if the SRL and data volumes with the required properties are available in the specified Secondary disk group. The following message displays in a window:

   The Secondary has been added.

8. Click Close. The Secondary RVG view for the newly added Secondary RVG is displayed.

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    Caution    If the data volumes on the Primary contain valid data, synchronize the Secondary data volumes with the Primary data volumes. See Synchronizing the Secondary and Starting Replication. Otherwise, see Setting Up Replication When Data Volumes are Initialized With Zeroes.

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