Channel-error during ndmp-backup from a netapp fas2554 to a lto-7-library. Also permanent open ndmp-sessionto the filer/tapes

Sometime at week we got a channel-error ("wrong session")  during backups (NetVault v12.4) from our netappfiler to tapelibrary.

We checked the logs and ask the netappsupport. During the backup I have a ndmpsession to the filer (ndmpserver/ primary storage) - this is correct.

I have also additional ndmpsessions to the filer (ndmpserver/ secundary storage = tapes) - this is correct. But this sessions are open after a check of the tapes or a backup, but never closed. The netappsupport see a problem in this fact.

(The supporter unfortunaly analyze the problem in the logs more).

What is your result of the command '  system services ndmp status' or ' vserver services ndmp status' after the backup is finish ? Are there ndmp-sessions more ?

The filer is a local 2-node device. The library is a LTO-7-system. All the devices are connected about a fibrechannel-switch.

[filer] --- [fc-swich-1]=========ISL===========[fc-swich-2]---+----[backup-server]


The MOVER (process on the filer) dedects this error after the data from the DATA-INTERFACE to the TAPE-/MOVER-IF are finished and the metadata send from the DMA to the filer/tape.