Netapp dump to tape command to troubleshoot NDMP backup issues (4033289)

NDMP attached tape device issues

Sometimes, there will be a need to troubleshoot NDMP backup issues between the Filer and the tape device to rule out an issue with the backup software. You will see sometimes errors like the ones below in the NetVault Binary logs, amongst several others and support may want to rule out any issue between the filer and the tape device.

Netapp backup failing with errors - NDMP error 34 - Backup Terminated Event 'Bad Media'

A good command to check this is to run a dump from Data Ontap console on the filer itself. It is important to understand that these dump commands are the same ones that NetVault invokes when doing an NDMP backup, so essentially, running the commands from Ontap will be doing the same thing, and potentially, produce the same result. Here is a basic command that can be run to test full dump to an tape drive attached to the filer.

There are a few things that need to be considered when doing backup using DUMP command:

1. Determine the Size of volume to be backed up.

   From the console or telnet session to the filer(telnet <ip address of filer>), 
   root>df -h path_name 
   e.g:- root>df -h /vol/vol1 (This will return size of the volume /vol/vol1) 

2. Estimating number of tapes to backup that volume.
   
   If the volume is 1 TB is size and you are using LTO4 drives, you would need 2 tapes.
   
   A simple Dump command:
   
   

   dump 0f nrst0a /vol/vol1
   Where,
   0 - indicates Full backup.
   f - indicates that backup will happen to a tape device specified.
   nrst0 - indicates a No-Rewind Sequential Tape device 0.
           (First tape drive. If you want to do it on second tape drive, use nrst1)
   a - indicates level of compression as the highest.
   /vol/vol1 - indicates the source volume to be backed.