Tech Alert: A potential for data loss has been discovered if a VMware Consolidated Backup (VCB) proxy backup joins an MPX (multiplex) group shared with other clients.

Problem

Tech Alert: A potential for data loss has been discovered if a VMware Consolidated Backup (VCB) proxy backup joins an MPX (multiplex) group shared with other clients.

Solution

Introduction
A potential for data loss has been discovered if a VMware Consolidated Backup (VCB) proxy backup joins an MPX (multiplex) group shared with other clients.  After the VCB backup has begun, successive backups of non-VCB clients may appear to complete successfully, exiting with a status code 0 (successful) in the Activity Monitor.   However, the VCB proxy host's local filesystem may be backed up in place of the filesystem of the host specified by the policy.

For instance, if the ALL_LOCAL_DRIVES directive is specified in the backup selection of an affected policy, the VCB proxy host's local file systems will be backed up instead of those of the client specified in the policy.  If specific file paths are placed in the backup selection, an attempt will be made to back up those paths on the VCB proxy host, which may result in an exit status code 71 (none of the files in the file list exist) in the Activity Monitor.

What is Affected:
Any environment where VCB proxy backups are configured may be affected.  This feature was introduced with the NetBackup 6.5.1 release update.

All client backups (file system or database) that join an MPX group after a VCB proxy backup has joined that group are affected.  Potentially, this could include many clients, depending on how the policies are configured.

Formal Resolution:
The formal resolution to this issue (Etrack 1416156) is included in the following patch release:
  • NetBackup 6.5 Release Update 3 (6.5.3)
NetBackup 6.5.3 is available at the Support web site at:
 http://www.symantec.com/business/support/downloads.jsp?pid=15143
Please note that the formal resolution will prevent this issue from occurring to future backups, but cannot recover data from affected backups.

Workarounds:
If applying the release update is not a feasible option, either of the following changes removes the VCB backups from the MPX group and allows correct operation:
1. Use a volume pool for the VCB backups separate from non-VCB backups.
2. Configure the VCB backups to use a separate storage unit from non-VCB backups.

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 your 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 as a Software Alerts, please subscribe at the following link:
 http://maillist.entsupport.symantec.com/subscribe.asp


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