Incremental or Differential network share backup fails with "Failed to initialize backup stream" (4044308)

Incremental or Differential network share backup fails with "Failed to initialize backup stream"

Incremental or Differential network share backup fails with "Failed to initialize backup stream" error.

Symptoms:
Network share Full Backup succeeds, however Differential or incremental backup of the same selection set fails.

Example of log messages:

Job Message 2011/04/13 09:46:23 46 Media SBACKDXB01 Media in 'IBM Ultrium:SBACKDXB01' assigned to job ready for data transfer Severe Error 2011/04/13 09:46:23 46 Data Plugin SBACKDXB01 Failed to initialize backup stream
Error 2011/04/13 09:46:23 46 Jobs SBACKDXB01 Fatal error: Backup failed

The error message "Failed to initialize backup stream" usually indicates a Data Plugin on a client is unable to make the TCP connection to a Device Manager hosted in another machine. This can usually be attributed to network connectivity or a lack of open Firewall ports.
Make sure that the Windows Firewall has been disabled on the NetVault Server.

As to why the full is succeeding and the Incremental / Differential fails:

NSB backup relies on NetVault 'impersonating' the "share user" to gain access to the share (as specified in the connect as configuration).

For a Full Backup, the data connection is made between File System Plugin and device processes.
Then the share user is impersonated by the File System Plugin process.
The share is read and data is written across the established data channel.

For an Incremental / Differential Backup, the File System Plugin has a slightly different order of operations.
Before the Incremental / Differential Backup issues a media request and makes the data connection, the File system performs a pre-scan.
In the case of NSB, this is the =network share= and the File System Plugin impersonates the "share user".
However the share user does not have access to the Device Manager Process, therefore cannot make the connection and this would generate the "Failed to initialize backup stream" error message.

For more information on this topic, please see the Administration Module 2-Basic Operation of NetVault Backup-Web-based Training

The solution to this is to have the NetVault product run as a user that has access to the share/s.
This will allow the data connection to be made by the file system process when it is impersonating the "share user".

This needs to be the local Administrator user to avoid any additional issues with internal NetVault operations:

1. Grant the NetVault Server Administrator user access to the share (with the same rights as the user configured within the NSB backup has).
2. Within the Windows Services and Applications GUI, change the user the NetVault Process Manager Service runs as from the local/system account to the Administrator account (Control Panel - Administrative Tools - Services - NetVault Process Manager - "Log On" tab).
3. Stop and restart NetVault Services (NetVault Configurator - Services tab).
4. Open the NetVault GUI - Backup item and select the File System Plugin. This is to check that you can browse the share with the Administrator user.
5. Open the File System Plugin and network shares node.
6. Select the relevant share listed (\\netappdxb1\vol4$).
7. Right click - select the "Connect As"� method and populate with the local administrator user details and click on OK.

BakBone SFDC Solution Number: 00006192