backup to tape reads MUCH more data that there is on disk

  • 8 December 2023

Userlevel 2



I recently installed B&R 12 Community Edition to backup a large file server to tape (about 36TB in one server).

The disk backup is done to a QNAP NAS connected via iSCSI to the HyperV Server that hosts the VM (needed to use iSCSI as the QNAP NAS does not support files larger than 16TB).

The backup to disk results in a 32TB VBK file. The tape drive is connected to another server running the Veeam Installation.

Running a Backup to Tape job on the (VSS snapshotted) backup folder however behaves weirdly: right now after 48 hours the job progress is 99% with 88,9 TB of 88,9 TB transferred to tape but that number keeps on growing to 89 TB of 89 TB and so on. Yesterday it was at 99% with 50 TB of 50 TB transferred.

The iSCSI target hosting the backup only has 50 TB in total disk space so reading 88 TB from that drive is rather unlikely.

The job states "Continuing task for <VBK-File>" and the task.<Hostname>.performer_1.log gives me the line after the last tape swap on the autoloader


[08.12.2023 01:16:11.690] <24> Info                 [AP] (c18f10e1) command: 'continueBackupSrvFileToTape\nTape0\nBackups-VEEAM/Backup Job 1/CCRAID02.0711b749-8653-4709-b1af-473f12aa673aD2023-12-04T203341_4FDB.vbk\n<incompleteFile name64="Q0NSQUlEMDIuMDcxMWI3NDktODY1My00NzA5LWIxYWYtNDczZjEyYWE2NzNhRDIwMjMtMTItMDRUMjAzMzQxXzRGREIudmJr" mtime="2023-12-06T07:48:38" ctime="2023-12-04T19:34:22" atime="2023-12-06T07:48:38" btime="2023-12-07T14:19:19" attributes="2048" continuation="true" fla="19075695105" dataSize="13953021478396" size="33486531948544" restSize="7783301221286" tapeNum="5" lastFla="25100812544" dirId="0" id="0" path64="XFw/XEdMT0JBTFJPT1RcRGV2aWNlXEhhcmRkaXNrVm9sdW1lU2hhZG93Q29weTJcQmFja3Vwcy1WRUVBTVxCYWNrdXAgSm9iIDFcQ0NSQUlEMDIuMDcxMWI3NDktODY1My00NzA5LWIxYWYtNDczZjEyYWE2NzNhRDIwMjMtMTItMDRUMjAzMzQxXzRGREIudmJr" sourceType="0"/>\n2\nTrue\n'


the hypervisor keeps on reading from \Device\HarddiskVolumeShadowCopy2\Backups-VEEAM\Backup Job 1\<VBK-File> at a rate of about 180 MB / sec and transmits 2.5 GBit (max rate of the NAS that hosts the iSCSI target) to the tape server.


any idea of what might be going on there?

this is the first backup of this system.


Best, Ulrich


Userlevel 7
Badge +17

Are there any additional errors?

In the message you have posted, I see:

b1af-473f12aa673aD2023-12-04T203341_4FDB.vbk\n<incompleteFile name64="Q0NSQUlEMDIuMDcxMWI3NDktODY1My00NzA5LWIxYWYtNDczZjEyYWE2N

Userlevel 2

I see no errors at all. my understanding is that “incompleteFile” refers to a file that spans multiple tapes?

Userlevel 7
Badge +17

I see no errors at all. my understanding is that “incompleteFile” refers to a file that spans multiple tapes?

It is possible that it is from the tape change. because of this I asked if there are other errors.

Would you like to share some screenshots of the job configuration? Please blur all sensitive information...

Userlevel 2

there ist not much to be configured… the advanced job options are left on default.

Veeam server is “CC-S-BACKUP” and runs Community Edition

Hypervisor and system that has the iSCSI target attached is standalone host CC-S-HV-R1 (and is the only host that us backed up with Veeam). I only runs one VM (with about 36 TB of allocated data)

VM that is being backed up is CCRAID02 but that should not be important as that is a seperate backup job that runs fine. Only the backup of the VBK file created by this first backup of the VM is being saved to tape by the job causing issues

“Files and Folders” of B2Tape Job
“Full Backup” settings
“Options” settings
Files to be backed up to tape



“Manage Volumes” of CC-S-HV-R1:


Userlevel 7
Badge +17

OK, so it is File-to-Tape Job and not a Backup-to-Tape Job.

Please configure a Backup-to-Tape Job for this.


Userlevel 2

Backup-to-Tape requires a Enterprise edition license, I have a Community edition license


Userlevel 7
Badge +17

Hi @Ulrich Wurst -

Just following up on your Tape post. Did you end up getting your question answered here? If so, can you mark which comment helped you as ‘Best Answer’ so others may benefit? If not, did you maybe reach out to Support or another resource? Can you share what you did to resolve this?

Thank you.