TECH ALERT: A potential for missed backups without notification may occur with frequency based schedules when either Cumulative Incremental's run less often than the Full, or Differential Incremental's run less often than the Full or Cumulative Incremental.

Article:TECH66362  |  Created: 2008-01-30  |  Updated: 2010-01-14  |  Article URL http://www.symantec.com/docs/TECH66362
Article Type
Technical Solution


Environment

Issue



TECH ALERT: A potential for missed backups without notification may occur with frequency based schedules when either Cumulative Incremental's run less often than the Full, or Differential Incremental's run less often than the Full or Cumulative Incremental.

Solution



Introduction:
A potential for missed backups without notification has been discovered in NetBackup Server/Enterprise Server with frequency based schedules when either Cumulative Incremental's run less often than the Full, or Differential Incremental's run less often than the Full or Cumulative Incremental in the same policy. This may result in a client backup not running during the scheduled window for any Differential Incremental or Cumulative Incremental frequency based schedule within this same policy.

Note: For the purpose of this document the following will apply:
-  Less often means the actual frequency value set in the schedule is a higher number.
-  More often means the actual frequency value set in the schedule is a lower number.


What is Affected:
NetBackup Server/Enterprise Server Master Servers, on all supported platforms for the following versions.
-  NetBackup Server/Enterprise Server 6.5.2 with version 6 or 7 of the nbpem binary applied *
-  NetBackup Server/Enterprise Server 6.5.2A with version 6 or 7 of the nbpem binary applied *
-  NetBackup Server/Enterprise Server 6.5.3 and release update 6.5.3.1

* In NetBackup Server/Enterprise Server 6.5.2 / 6.5.2A the nbpem binaries that exhibit this issue are only available from Symantec by contacting Symantec's Enterprise Technical Support. If no nbpem binaries have been obtained and applied from support, this issue will not occur on 6.5.2/6.5.2A.  These binaries are not installed with a standard NetBackup installation and must be manually placed on the Master Server. To determine if a nbpem binary has been applied to the Master Server run 'versioninfo' against nbpem.

Windows:
<install_path>\NetBackup\bin\goodies\versioninfo.exe -f <path and file to be checked>

UNIX:
usr/openv/netbackup/bin/goodies/support/versioninfo -f <path and file to be checked>

The following versioninfo output strings from 6.5.2 nbpem binaries obtained from Support may be affected:
-  NetBackup_6.5.2A_EEB1_PET1322971_SET1448343
-  NetBackup_6.5.2A_EEB1_PET1386189_SET1481246
-  NetBackup_6.5.2A_EEB1_PET1519933_SET1519931
-  NetBackup_6.5.2A_EEB6_PET1409915_SET1409664


How to Determine if Affected:
If ALL of the following conditions are true, a missed backup has been known to occur:
-  The Master Server is running one of the affected versions above on a supported platform
-  The nbpem binary version 6 or 7 has been obtained by support and applied to the Master Server or the NetBackup 6.5.3 / 6.5.3.1 release update has been applied
-  Frequency based schedules are in use
-  Cumulative Incremental or Differential Incremental schedules are in use in this policy
-  The Differential Incremental runs less often than the Full or Cumulative Incremental (see examples # 1 below)
OR
-  The Cumulative Incremental runs less often than the Full (see example # 2 below)
-  A backup is missed due to this issue

If all of these conditions occur, any Cumulative Incremental or Differential Incremental frequency based schedule in this policy may be skipped.

Example1:
-  A 6.5.2 NetBackup Master Server has a "version 6" nbpem  EEB applied which was supplied from support
-  Within a policy, a Differential Incremental frequency based schedule is configured with a frequency of every 5 days
-  This Differential Incremental has an open window only on Saturday
-  This same policy also has a Cumulative Incremental frequency based schedule with a frequency of every 1 day
-  The Cumulative Incremental has an open window of Monday - Friday
-  On Friday, the Cumulative Incremental backup runs.
-  The Cumulative Incremental backup completes successfully
-  On Saturday, the Differential Incremental backup does not run due to this issue

In this example, the client Differential Incremental backup will be missed every Saturday.

Example2:
-  A 6.5.3 NetBackup Master Server
-  Within a policy, a Cumulative Incremental frequency based schedule is configured with a frequency of every 7 days
-  This Cumulative Incremental has an open window only on Sunday
-  This same policy also has a Full frequency based schedule with a frequency of every 1 day
-  The Full has an open window of Monday - Saturday
-  On Saturday, the Full backup runs
-  The Full backup completes successfully
-  On Sunday, the Cumulative Incremental frequency based schedule does not run due to this issue

In this example, the client Cumulative Incremental backup will be missed every Sunday.


Workarounds:
There are two different available workarounds for this issue. They are listed in relation to the examples shown above.

1. Change the frequency of the Differential Incremental to be equal too or less than the frequency value of the Cumulative Incremental and/or Full schedule.  In example 1 the frequency value of the Differential Incremental would need to be set to a value of 1. The open window can be left to Saturday only.

2. Change the frequency of the Cumulative Incremental to be equal too or less than the frequency value of the Full schedule. In example 2 the frequency value of the Cumulative Incremental would need to be set to a value of 1. The open window can be left to Sunday only.

If these workarounds are not feasible or the formal resolution cannot be applied, please contact Symantec Technical Services, referencing this TechNote ID (317006) and Etrack 1473722.

Formal Resolution:
The formal resolution to this issue is tentatively scheduled to be included in the following patch release:

-  NetBackup 6.5 Release Update 4 (6.5.4), currently scheduled for release in the second quarter of 2009.


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


Supplemental Materials

SourceETrack
Value1473722
DescriptionWindows weekly cumulative backups do not run after applying nbpem v6


Legacy ID



317006


Article URL http://www.symantec.com/docs/TECH66362


Terms of use for this information are found in Legal Notices