Veritas NetBackup (tm) Catalog Replication: Conditional Support Statement.

  • Article ID:100018113
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This statment applies for versions of NetBackup up to and including NetBackup 7.0.

For NetBackup 7.0.1 and higher versions the conditions of support are detailed in the NetBackup Highly Available Environments Administrator's Guide for the relevant NetBackup version.


Support for NetBackup Catalog Replication

This document defines the conditions that must be met to allow the replication of the live NetBackup catalog between primary and secondary master servers.  Operation of NetBackup in this way is subject to the following constraints:
1. The replication technology employed must maintain a consistent (i.e. write-ordered) copy of the data at all times.
2. The use of asynchronous replication technologies is permitted provided suitable provisions are in place to ensure write order fidelity is maintained.
3. The use of scheduled replication technologies such as hourly snapshots is NOT supported.
4. The NetBackup Master Server and EMM Server must reside on the same virtual server controlled as a single entity.
5. The primary and secondary master servers must be of similar type, specification and operating system  and use the same virtual host name.
6. The secondary master server should not have any other NetBackup  function, either in the same domain as the primary master server or in another domain (e.g. the secondary master server  cannot be used as a media server when it is not being used as a master server, nor can it be the master server for another NetBackup domain - catalogs are replicated but cannot be merged).
7. All master servers must be running NetBackup version 6.5.4 or above.  (Customers running existing clustered configurations on NetBackup 6.0 MP4 and above are advised to upgrade to NetBackup 6.5.4.)
8. Both clustered and non-clustered environments should be configured to use a 'virtual' hostname and IP address for the NetBackup master server that is separate from the physical host names and IP addresses of the servers.   This enables the user to control the active master server node through DNS routing and helps to reduce the risk of both primary and secondary master servers appearing active in the domain at the same time.  For clustered environments this requirement is met automatically by the cluster configuration.  For non-clustered environments the virtual hostname must be specified at installation time.
9. Site operational procedures must be in place to ensure that the version of NetBackup and dependent components are the same on the primary master server and the secondary master server.  This includes the operating system and NetBackup binaries, EEBs and configurations files not included in the paths that are specified for replication.
10. Replication between clustered and non-clustered master servers is not possible - server pairs must be either clustered or non-clustered.
11. The NetBackup catalog mount point must be the same at both primary and secondary sites.
12. Only the catalog data is replicated between servers and must all be co-located on a single volume or volume set for replication.  For clustered master servers this means the cluster common volume is replicated.  For non-clustered master servers refer to article 345978 for details of the paths that must be linked to a volume set for replication.  
13. Appropriate steps must be taken to ensure that the virtual name/DNS alias does not resolve to both primary and secondary hosts at the same time.
14. Catalog replication does not remove the requirement for catalog backup.  Regular backups of the NetBackup catalog must still be made from the primary master server as a protection against accidental image expiration or other inconsistencies introduced into the catalog on the primary side and replicated to the secondary site.
15. Where catalogs are replicated between NetBackup domains (rather than to a secondary server that can access the primary domain's media servers) only backups written to tape and replicated BasicDisk storage can be restored in the disaster recovery domain.  
16. Replication of the catalogs to a secondary server as described in this document allows data to be restored during a short term outage of the primary master server.  Additional steps will be required, particularly in cross domain replication configurations, to ensure that backups can be run after a fail over and the catalogs can be failed back to the primary server at a later date without data loss.  Customers are encouraged to regard this as a part of a broader DR strategy and to consider how they would go about making backups at the DR site during a prolonged outage and then moving back to the primary site without losing information about backups created at the DR site.  
17. The ability to bring NetBackup up using the replicated copy on the secondary site should be verified as part of the initial configuration. This is not a requirement for support.
18. It must be emphasized that both catalog and backup images must be accessible at the secondary site.  The catalog replication capability discussed in this note does not address the availability of valid copies of the backup images, nor of the procedures required to enable the NetBackup server to restore from the images at the secondary site. These requirements must be addressed by site procedures.
19. The customer is responsible for installing, configuring and monitoring their data replication solution to ensure that the replication technology employed continuously maintains a consistent write-ordered copy of the NetBackup catalog volume.  

Conditions of support

Customers can expect the same level of support for a NetBackup environment which has been configured in accordance with the constraints defined above to that for any other NetBackup server, with the exception that if it is determined that a failure of the replicated catalog volume which is unrecoverable within a reasonable time scale has occurred, NetBackup support recommendations will be the same as those which would be effected in the case of an unrecoverable disk failure of a  non-replicated catalog. It should be noted that the recommendation in this case would be to restore the catalog from the latest available catalog backup created on the primary master server.


Customers are advised to note the following points about the use of replication:
There is a risk of data loss with any data replication solution - replication technology should not solely be relied upon to protect the NetBackup Catalog due to the risk of failure of the replication technology or the risk that a failure or corruption of data on the primary NetBackup Server could be propagated via replication to the secondary hot-standby NetBackup Server. Therefore, frequent catalog backups of the NetBackup Server must also be performed according to the documented catalog backup procedures in addition to any supported replication solution.
Replication can adversely affect application performance - it should be noted that in extreme circumstances the use of replication technologies can degrade the performance of NetBackup as extended time required to commit changes to the NetBackup catalog may impact overall backup times.
You may use replication at your sole risk and Veritas shall have no liability for any replication failure based on your failure to properly install, configure and monitor your replication solution.
Further reading
The following documents provide more details on specific configurations:
  • Configuring and operating catalog replication with clustered master servers (TN 345978)
  • Configuring and operating catalog replication with non-clustered masters (TN 345977)
  • Recovery procedures when replicating NetBackup catalogs between primary and disaster recovery domains (TN 345979)

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