A potential for data loss has been discovered in NetBackup Enterprise Server when backing up hard links on a Windows 2008 Server or Vista client, if these hard links are also Shadow Copy Components. This does not affect user data at this time.

Article:TECH67128  |  Created: 2009-01-30  |  Updated: 2009-01-30  |  Article URL http://www.symantec.com/docs/TECH67128
Article Type
Technical Solution

Product(s)

Environment

Issue



A potential for data loss has been discovered in NetBackup Enterprise Server when backing up hard links on a Windows 2008 Server or Vista client, if these hard links are also Shadow Copy Components. This does not affect user data at this time.

Solution



Introduction:
A potential for data loss has been discovered in NetBackup Enterprise Server when backing up hard links on a Windows 2008 Server or Windows Vista client if these hard links are also Shadow Copy Components.  This issue is known to affect system components only.  Therefore, the issue is encountered when performing a full system restore, rather than a restore of user data.  Since some system components may not be backed up due to this issue, a restore procedure using the operating system (OS) install files should be possible to lead to full recovery.

Many Windows 2008 Server Operating System files are Hard Links.  NetBackup is capable of backing up and restoring a Hard Linked file on Windows Server 2008 or Vista.   However, when such a file is categorized as a Shadow Copy Components:\ subcomponent, these files will not be available for direct recovery from the backup set.

What is Affected:
NetBackup Server/Enterprise Server Master Servers, on Windows 2008 Server or Windows Vista (x86 and x64) for the following versions:
-  NetBackup Server/Enterprise Server 6.0.MP6 through NetBackup Server/Enterprise Server 6.5.1 (Windows Vista only)
-  NetBackup Server/Enterprise Server 6.5.2 through NetBackup Server/Enterprise Server 6.5.3.1 (Windows Vista and Windows Sever 2008)


How to Determine if Affected:
Data loss has been known to occur if ALL of the following conditions have been met:
- A NetBackup client is running one of the NetBackup versions mentioned above, on a supported Windows Vista or Windows Server 2008 platform.
- The client is configured for a full system backup, including Shadow Copy Components:\.
- Shadow Copy Components:\ on the client include one or more files that are hard links.
- Backup completes with a Status 0, however hard link files within Shadow Copy Components are not backed up.
- A full system restore is desired and performed at a later time, completing with a Status 0.  However system components are missing due to this issue.

Note: If a hard link utility is manually used to create hard linked files in OS other than 2008 or Vista that are classified as Shadow Copy component, this issue may also result in that OS and any supported NetBackup version.  However, by default, hard links currently only exist in Windows 2008 Server or Windows Vista.


Workaround:
Ensure that when performing a disaster recovery of a Windows 2008 Server or Vista client, that all system components and service packs are installed before performing a restore.  This issue affects system recovery for Windows 2008 Server and Windows Vista, but may only be noticed or exposed when recovering specific server roles, such as Active Directory.  In the case of a standard Windows 2008 or Vista install, this issue should normally be transparent as a disaster recovery would normally involve a full re-installation of the operating system, thereby replacing the components that are not available in the backup set.

Only system components are known to be affected by this issue, not user data.  Therefore, an alternate restore procedure utilizing the Operating System install files will be necessary.  No user data should be permanently lost due to this issue.

See the Related Documents section below for information on Hard Links in Windows 2008 as well as instructions on recovery for specific server roles / configurations where this issue has been encountered.    


Formal Resolution:
The formal resolution to this issue will be included in the following release update:
- NetBackup Server/Enterprise Server 6.5.4, tentatively scheduled for release in Q2 of calendar year 2009.

When 6.5.4 is released, please refer back to this document's Related Document section for links to the fixes, or subscribe to this article as mentioned below.


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:
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If further information becomes available, this document will be updated accordingly.  Subscribe to this document directly to be informed of any changes by clicking the following link:    http://maillist.support.veritas.com/notification.asp?doc=318083

Supplemental Materials

SourceETrack
Value1506354
DescriptionETrack (NetBackup) 1506354, 1542964: Recovery of Windows 2008 Domain Controller fails.


Legacy ID



318083


Article URL http://www.symantec.com/docs/TECH67128


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