Overview
Symantec has identified a critical issue in Storage Foundation for Windows (SFW) with the Veritas Volume Replicator (VVR) option.  After performing a successful migration to the secondary site, there will be data missing from the secondary site.

This issue is caused by data sent by Primary to Secondary being silently ignored by Secondary, if the Secondary RVG had srl_header_err flag set.

The reason for the data difference between Primary and Secondary is due to the srl_header_err flag set on Secondary. The mapping of the volumes between Primary and Secondary is stored in Replicator log header. If srl_header_err flag is set, this mapping information is not updated on the Secondary. Data that the Primary sends is ignored by the Secondary, since it does not find the data volume to update it with, causing the data difference between Primary and Secondary.

What's Affected
This issue is present in the following versions:

This applies to all Windows supported operating system versions with the above products.

How to Determine if Affected
This issue will occur if all of the following conditions are met:

Formal Resolution
WARNING: A full resynchronization is required after applying the fix to this issue (refer to the VVR Admin Guide, link below in the Related Documents section, for the definition of a full resynchronization).  

This fix has not been fully tested. It is recommended that the fix be evaluated in a test environment before implementing it in your production environment. When the fix is incorporated into a Storage Foundation for Windows maintenance release, the resulting Hotfix or Service Pack must be installed as soon as possible. Symantec Technical Services will notify you when the maintenance release (Hotfix or Service Pack) is available.

To resolve this issue, apply the patch linked to this article by clicking on the "Download Now" link, below, to begin installation. Verify that the correct version of the patch is installed according to product version.   Note:  Be sure to use the correct files for your operating system. Using the wrong files may result in an Blue Screen of system. If you are unsure which files to use, contact Symantec Enterprise Technical Support before installing the replacement files.  

This behavior of VVR with regards to the way the secondary handles a Replicator Log header error has been altered so that the VVR Secondary notifies the VVR Primary of the error and replication is stopped. This causes the VVR Secondary to remain consistent but causes the VVR Secondary to become out of date with the VVR Primary. Once the Replicator Log header error is resolved then replication to the VVR Secondary from the VVR Primary will continue from the last successful write from before the VVR Secondary had the Replicator Log header error.

Additional Patch Information:
This patch also contains cumulative private fixes for SFW-VVR version 5.0 and SFW-VVR version 5.0 Rp1a for the following issues:

SFW - 5.0 GA
1. Adjusting data message sequencing on Primary based on acknowledgments received from Secondary.
2. Secondary log error during secondary log replay.
3. System crash during in-band control receive

SFW - 5.0 RP1a
1. Adjusting data message sequencing on Primary based on acknowledgements received from Secondary.
2. Secondary log error during secondary log replay.
3. System crash during in-band control receive

Refer to the following reference documents for additional information regarding the "additional" fixes contained in the Download Now link, below:
 http://entsupport.symantec.com/docs/304475

and

 http://entsupport.symantec.com/docs/303841



Best Practices
Symantec strongly recommends the following best practices:
1. Always perform a FULL backup prior to and after any changes to your environment.
2. Always make sure that the environment is running the latest version and patch level.

How to Subscribe to Software Alerts
If you have not received this TechNote from the Symantec Email Notification Service for Software Alerts, please subscribe at the following link:    http://maillist.support.veritas.com/