Exchange Server APM 4.5.X- Failed to backup file 'eXXtmp.log' (4047320)

Backups of Exchange 2010 fail with the following log errors.

Warning 2010/07/14 21:09:13 924 Data Plugin EXCH Failed to backup file 'E00tmp.log'
Error 2010/07/14 21:09:13 924 Data Plugin EXCH Failed to back up log files for database 'MailboxDB1'
Error 2010/07/14 21:09:13 924 Data Plugin EXCH Failed to backup logs for database 'MailboxDB1'
Error 2010/07/14 21:09:13 924 Data Plugin EXCH Aborting the stream for database MailboxDB1 due to failure
Error 2010/07/14 21:13:11 924 Data Plugin EXCH Failed to write index of backup to the database
Error 2010/07/14 21:18:13 924 Data Plugin EXCH Failed to connect to job manager

All selected items have been backed up except for one (or several) Enntmp.log file.

Under Exchange Server APM 4.5.6, the default backup method is VSS.
The Exchange VSS Writer performs a snapshot that will then be backed up by NetVault.
When Circular Logging is enabled, the snapshot is missing the Enntmp.log file which causes NetVault to log it as an error and fail the job.

Background:
For each Mailbox Database transactions are written to Enn.log (nn being the Storage group or Database number: 00 for the first, 01 for the second...).
When Enn.log is full (1024KB), it is 'archived', ie renamed to eg. Enn00001af.log.
While Enn.log is archived Exchange carries on writing current transations to Enntmp.log, which will in turn be renamed to Enn.log.
Essentially when Enn.log is full 2 rename operations occur:
Enn.log ----> to e.g. Enn000001af.log
Enntmp.log ----> to Enn.log

Disable Circular logging on all Mailbox Databases to be backed up:
From Exchange Management Console right click each Mailbox Database to backup > Properties > Maintenance > uncheck "Enable Circular Logging"

Disabling Circular logging is a pre-requisite described in the Exchange Server APM user's guide:

http://usdownloads.quest.com.edgesuite.net/Repository/support.quest.com/NetVault%20Backup/8.6.1/Documentation/Plugin%20for%20Exchange/NetVault_Backup_APM_for_Exchange_Server_Users_Guide.pdf

If Circular logging is enabled, incremental and differential backups are not possible as the Exchange logs are constantly overwritten,
preventing any chances to perform point in time recoveries.

Date - Sept-2010
Affected Product & Version - NetVault:Backup 8.5.x and greater
Affected Module & Version - Exchange Server APM 4.5.X and greater
OS Version - Windows Server 2008
Application Information - Exchange Server 2010
 

BakBone SFDC Solution Number: 00005848