Storage Foundation and High Availability Solutions 7.4.2 Solutions Guide - Windows

To create the Replicated Data Set

1. Use the Veritas Enterprise Administrator (VEA) console to launch the Setup Replicated Data Set Wizard from the cluster node on the Primary where the cluster disk group is imported.

   Start Veritas Enterprise Administrator from the Apps menu on the Start screen, and click View > Connection > Replication Network.

2. Right-click Replication Network and select Setup Replicated Data Set.
3. Read the information on the Welcome page and then click Next.
4. Specify names for the Replicated Data Set (RDS) and Replicated Volume Group (RVG) and then click Next.
   

   By default, the local host is selected as the Primary Host. To specify a different host name, make sure the required host is connected to the VEA console and select it in the Primary Host list.

   If the required primary host is not connected to the VEA console, it does not appear in the drop-down list of the Primary Host field. Use the VEA console to connect to the host.

5. Select from the table the dynamic disk group and data volumes that will undergo replication and then click Next.
   

   To select multiple volumes, press the Shift or Control key while using the up or down arrow keys.

   By default, a mirrored DCM log is automatically added for all selected volumes. If disk space is inadequate to create a DCM log with two plexes, a single plex is created.

6. Complete the Select or create a volume for Replicator Log page as follows:
   

   To select an existing volume

   • Select the volume for the Replicator Log in the table (APP_REPL_LOG). If the volume does not appear in the table, click Back and verify that the Replicator Log volume was not selected on the previous page.

   • Click Next.

   To create a new volume

   • Click Create Volume and enter the following information in the dialog box that appears:

     Name	Enter the name for the volume in the Name field.
     Size	Enter a size for the volume in the Size field.
     Layout	Select the desired volume layout.
     Disk Selection	Enables you to specify the disk selection method. Enable the Thin Provisioned Disks Only check box to ensure that the Replicator Log volume is created only on Thin Provisioned (TP) disks. Note: The check box will remain disabled if the diskgroup does not have any TP disk. If this option is selected along with the Select disks automatically option, then the Replicator Log volume will be created only on TP disks. However, if you enable this check box along with Select disks manually option, then the user can select only TP disks from Available Disks. For more information on Thin Provisioning, refer to the Storage Foundation Administrator's Guide. Choose the Select disks automatically option if you want Volume Replicator to select the disks. Choose the Select disks manually option to use specific disks from the Available disks pane for creating the volume. Either double-click on it or select Add to move the disks into the Selected disks pane.

   • Click OK to create the Replicator Log volume.

   • Click Next in the Select or create a volume for Replicator Log dialog box.

7. Review the information on the summary page and click Create Primary RVG.
8. After the Primary RVG has been created successfully, Volume Replicator displays the following message:

   RDS with Primary RVG has been created successfully. 
   Do you want to add Secondary host to this RDS for replication now?
   

   Click No to exit the Setup Replicated Data Set wizard without adding the Secondary host. To add the Secondary host later, use the Add Secondary option from the RDS right-click menu.

   Click Yes to add the Secondary host to the Primary RDS now. The Specify Secondary host for replication page appears.

9. On the Specify Secondary host for replication page, enter the name or IP address of the Secondary host in the Secondary Host field and then click Next.

   If the Secondary host is not connected to VEA, the wizard tries to connect it when you click Next. This wizard allows you to specify only one Secondary host. Additional Secondary hosts can be added using the Add Secondary option from the RDS right-click menu.

   Wait till the connection process is complete and then click Next again.

10. If only a disk group without any data volumes or Replicator Log, as on the Primary host exists on the Secondary, then Volume Replicator displays a message. Read the message carefully.

    The option to automatically create volumes on the Secondary host is available only if the disks that are part of the disk group have:

    • The same or larger amount of space as that on the Primary

    • Enough space to create volumes with the same layout as on the Primary

      Otherwise, the RDS setup wizard enables you to create the required volumes manually.

    • Click Yes to automatically create the Secondary data volumes and the Replicator Log.

    • Click No to create the Secondary data volumes and the Replicator Log manually, using the Volume Information on the connected hosts page.

11. The Volume Information on connected hosts page appears. This page displays information on the availability of volumes on the Secondary nodes, if the Primary and Secondary hosts are connected to VEA.

    This page does not appear if all the required volumes that are available on the Primary host are also available on the Secondary hosts.

    • If the required data volumes and the Replicator Log have not been created on the Secondary host, then the page displays the appropriate message against the volume name on the Secondary.

    • If an error occurs or a volume needs to be created, a volume displays with a red icon and a description of the situation. To address the error, or to create a new Replicator Log volume on the secondary site, click the volume on the secondary site, click the available task button and follow the wizard.

      Depending on the discrepancies between the volumes on the primary site and the secondary site, you may have to create a new volume, recreate or resize a volume (change attributes), or remove either a DRL or DCM log.

      When all the replicated volumes meet the replication requirements and display a green check mark, click Next.

    • If all the data volumes to be replicated meet the requirements, this screen does not occur.

12. Complete the Edit replication settings page to specify the basic and advanced replication settings for a Secondary host as follows:
    

    • To modify each of the default values listed on this page, select the required value from the drop-down list for each property. If you do not wish to modify basic properties then replication can be started with the default values when you click Next.

      Primary side	IP Enter the virtual IP address for the Primary IP resource that will be used for replication. If there is more than one IP address available for replication, you can choose the one that you want to use from the drop-down list. If the required IP address is not displayed in the list then edit the field to add the IP address.
      Secondary side IP	Enter the virtual IP address on the Secondary that is to be used for replication. If there is more than one IP address available for replication, you can choose the one that you want to use from the drop-down list. If the required IP address is not displayed in the list then edit the field to add the IP address.
      Replication Mode	Select the required mode of replication: Synchronous Override (default) enables synchronous updates under typical operating conditions. If the Secondary site is disconnected from the Primary site, and write operations occur on the Primary site, the mode of replication temporarily switches to Asynchronous. Synchronous determines updates from the application on the Primary site are completed only after the Secondary site successfully receives the updates. Asynchronous determines updates from the application on the Primary site are completed after Volume Replicator updates in the Replicator Log. From there, Volume Replicator writes the data to the data volume and replicates the updates to the secondary site asynchronously. If the Secondary is set to the synchronous mode of replication and is disconnected, the Primary data volumes with NTFS file systems may be displayed with the status as missing.
      Replicator Log Protection	AutoDCM is the default selected mode for the Replicator Log overflow protection when all the volumes in the Primary RVG have a DCM log. The DCM is enabled when the Replicator Log overflows. The DCM option enables the Replicator Log protection for the Secondary host when the Replicator Log overflows, and the connection between the Primary and Secondary is lost. This option is available only if all the data volumes under the Primary RVG have a DCM Log associated with them. The Off option disables Replicator Log Overflow protection. In the case of the Bunker node. Replicator Log protection is set to Off, by default. Thus, if the Primary RLINK overflows due to the Bunker RLINK, then this RLINK is detached. The Override option enables log protection. If the Secondary node is still connected and the Replicator Log is about to overflow then the writes are stalled until a predetermined amount of space, that is, 5% or 20 MB (whichever is lesser) becomes available in the Replicator Log. If the Secondary becomes inactive due to disconnection or administrative action then Replicator Log protection is disabled, and the Replicator Log overflows. The Fail option enables log protection. If the log is about to overflow the writes are stalled until a predetermined amount of space, that is, 5% or 20 MB (whichever is lesser) becomes available in the Replicator Log. If the connection between Primary and Secondary RVG is broken, then, any new writes to the Primary RVG are failed.
      Primary RLINK Name	This option enables you to specify a Primary RLINK name of your choice. If you do not specify any name then Volume Replicator assigns a default name.
      Secondary RLINK Name	This option enables you to specify a Secondary RLINK name of your choice. If you do not specify any name then Volume Replicator assigns a default name.

    • If you want to specify advanced replication settings, click Advanced. Edit the replication settings for a secondary host as needed.

      

      Caution:

      When determining the high mark and low mark values for latency protection, select a range that is sufficient but not too large to prevent long durations of throttling for write operations.

      Latency protection	Determines the extent of stalling write operations on the primary site to allow the secondary site to "catch up" with the updates before new write operations can occur. Off is the default option and disables latency protection. Fail enables latency protection. If the number of outstanding write operations reaches the High Mark Value (described below), and the secondary site is connected, Volume Replicator stalls the subsequent write operations until the number of outstanding write operations is lowered to the Low Mark Value (described below). If the secondary site is disconnected, the subsequent write operations fail. Override enables latency protection. This option resembles the Off option when the secondary site is disconnected, and the Fail option when the secondary site is connected. Throttling of write operations affects application performance on the primary site; use this protection only when necessary according to replication throughput and application write patterns.
      High Mark Value	Is enabled only when either the Override or Fail latency protection option is selected. This value triggers the stalling of write operations and specifies the maximum number of pending updates on the Replicator Log waiting for replication to the secondary site. The default value is 10000, the maximum number of updates allowed in a Replicator Log.
      Low Mark Value	Is enabled only when either the Override or Fail latency protection options is selected. After reaching the High Mark Value, write operations on the Replicator Log are stalled until the number of pending updates drops to an acceptable point at which the secondary site can "catch up" to the activity on the primary site; this acceptable point is determined by the Low Mark Value. The default value is 9950.
      Protocol	UDP/IP is the default protocol for replication.
      Packet Size	Updates to the host on the secondary site are sent in packets; the default size 1400 bytes. The option to select the packet size is enabled only when UDP/IP protocol is selected.
      Bandwidth	By default, Volume Replicator uses the maximum available bandwidth. To control the bandwidth used, specify the bandwidth limit in Mbps.
      Enable Compression	Enable this checkbox if you want to enable Compression for the secondary host.

      Click OK to close the dialog box and then click Next.

13. On the Start Replication page, choose the appropriate option as follows:

    • To add the Secondary and start replication immediately, select Start Replication with one of the following options:

      Synchronize Automatically

      If virtual IPs have been created, select the Synchronize Automatically option, which is the default recommended for initial setup to start synchronization of Secondary and start replication immediately. If the virtual IPs for replication are not yet created, automatic synchronization remains paused and resumes after the Replication Service Group is created and brought online. When this option is selected, Volume Replicator by default performs intelligent synchronization to replicate only those blocks on a volume that are being used by the file system. If required, you can disable intelligent synchronization. Note: Intelligent synchronization is applicable only to volumes with the NTFS and ReFS file systems and not to raw volumes or volumes with FAT/FAT32 file systems.

      Synchronize from Checkpoint

      If you want to use this method, then you must first create a checkpoint. If you have considerable amount of data on the Primary data volumes, then you may first want to synchronize the secondary for existing data using the backup-restore method with checkpoint. After the restore is complete, use the Synchronize from Checkpoint option to start replication from checkpoint to synchronize the secondary with the writes that happened when backup-restore was in progress. For information on synchronizing from checkpoints, refer Volume Replicator Administrator's Guide.

    • To add the secondary without starting replication, deselect the Start Replication option. You can start replication later by using the Start Replication option from the Secondary RVG right-click menu.

    • Click Next to display the Summary page.

14. Review the information.

    Click Back to change any information you had specified.

    Otherwise, click Finish to add the secondary host to the RDS and exit the wizard.