NDMP data does not start on a block boundary. (4046074)

Date – 02/2010
Affected Product & Version – NetVault: Backup 8.x, 9.x, 10.x
Affected Module & Version – All NDMP
OS Version - all
Application Information – n/a


Description:
Due to an NDMP block size dependency, the block size of the restoring device or restore session must be the same as the original backup.
This can occur in the following circumstances:
Scenario-1. Backup of a filer to drive 1 that has block size X, but load the tape for restore into drive 2 that has block size Y.
Scenario-2. Backup of a filer to VTL with block size X, then duplicate or datacopy that job from VTL to physical tape with block size Y and try to restore from physical tape.


Symptoms:
The restore will fail with the errors.
NDMP data does not start on block boundary
[device] had a channel error
Failed to start NDMP transfer

The last line from log context of the channel error shows:
DEVMOVER:01496 736 0 11014 NDMP data does not start on a block boundary Block size 65536ListenPositionInStream 32768

In Scenario-1, make sure that the restore job uses a tape drive that has block size X.
In Scenario-2, the physical tape must be datacopied back to the VTL. Ensure that the source physical tape drive has block size Y, and the VTL source drive has block size X.
In the example error above, Y = 65536bytes, and X = 32768bytes.

Note that this problem can also occur for Netware backups or Bare Metal Recovery (BMR/VaultDR) backups. These use the NDMP protocol.