Failure backing up files via UNC path on a Windows 2008 NetBackup Client

Problem

It is possible to configure a NetBackup Policy specifying Client-A, but with a Backup Selection of a UNC path pointing to Client-B. In this way, it is possible to use a Windows Client as a conduit to backup data residing on remote hosts.

This is a common practice if the remote host is a Filer on which installing the NetBackup Client Agent is not an option.

Error Message

The error may manifest itself in these ways:

1. The Job may fail with Status 13/42 in Activity Monitor due to an application fault of bpbkar32.exe on the client
2. The faulting bpbkar32.exe process on the client will produce an error in the Windows Application Event Log:
Example: Fri Feb 11 2011 13:57:47 Application Error E1000 Faulting application name: bpbkar32.exe, version: 7.0.2010.707, time stamp: 0x4c475004
 

Cause

After in-depth examination of the situation by both Symantec and Microsoft engineering it was discovered that changes made to Windows 2008 and Windows 2008R2 specific to SMB 2.0 (also known as CIFS), can cause a timing error in the file read operation performed by the API which NetBackup uses to read files (NTIO) which results in a NULL_POINTER_WRITE which causes bpbkar32.exe to fault.
 

Solution

There are several workarounds for this issue which can be employed depending on preference:

1. If the machine on which the data resides is an NDMP filer, use the NetBackup NDMP feature to read the data directly off the filer.  This is also known to improve backup performance.

2. Because SMB 2.0 is new with Windows 2008, specify a Windows 2003 (SMB 1.0) NetBackup Client to use as a passthrough host to backup the data.

3. In order to use SMB 2.0, hosts on both sides must be capable of using it.  If either side of the conversation is using SMB 1.0, the other must also use SMB 1.0.  Therefore disabling SMB 2.0 on either the Windows 2008 NetBackup Client or disabling SMB 2.0 on the filer should resolve the problem.

NOTE: Reference Microsoft articles on how to disable SMB 2.0 and or contact the appropriate filer vendor to find out more about disabling SMB 2.0 on the filer. 
This Microsoft Article discusses a performance issue with SMB 2.0 with steps to revert back to SMB 1.0 support.microsoft.com/kb/950836

4. On the Windows 2008 NetBackup Client, disable the Symantec API called NTIO.  This will cause NetBackup to use the Microsoft API called 'BackupRead' - which does not encounter the same timing error.

STEPS TO DISABLE NTIO
1. Click Start | Run, type regedit, and click OK
Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.
2. Browse to HKEY_LOCAL_MACHINE\Software\VERITAS\NetBackup\CurrentVersion\Config
3. In the Config registry key, create a new key called NTIO
4. In the NTIO registry key, create a REG_DWORD value, give it the name UseNTIO and the value decimal  0 (zero) 

 

NOTE: In some rare instances bpbkar32.exe has also been observed to fault with SAN attached disk for the same reason.

NOTE: NetBackup 7.5 will create the UseNTIO registry key (set to '0') by default during installation on Windows, thereby disabling the use of NTIO by default.

 


Applies To

Windows 2008  (32 bit or 64 bit)
Windows 2008R2  (64 bit)

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