Maximum Concurrent NDMP Sessions (4046505)

Date – 04/10
Affected Product Version – NVBU 8.x and prior
Affected Module & Version - NDMP
OS Version - All
Application Information – N/A

Description:
Maximum Concurrent NDMP Sessions

Symptoms:
NDMP backup fails after submitting 40 child backup jobs.

The NDMP Spec calls for a maximum of 32 concurrent NDMP Sessions
Cut the backup into smaller parts so we don’t exceed a maximum of 32 NDMP Sessions

this can be caused by a filer with a large number of volumes spawning large number of ndmp subjobs (1 per volume) being submitted at the same time.

To prevent this from happening without having to subdivide the backup jobs limit the number of sub jobs that can be executed in parallel by using the ndmp backup option
"Number of backups to run in parallel (0 == All)"

Ideally you will want to set this to the number of tape drives available that falls within the number of NDMP sessions that the filer will support

i.e. if you have a filer with 50 volumes 8 available tape drives and the filer supports 10 NDMP sessions , then set this value to 8 and the netvault will execute the 50 subjobs in batches of 8

As described within NetVault_Backup_NDMP_Application_Notes_NetApp_ONTAP

http://docs.bakbone.com/docs/NetVault_Backup_NDMP_Application_Notes_NetApp_ONTAP.pdf


section 3.2.2.c Sub Jobs -

In the Sub Jobs frame, configure the
following parameters:
Number of backups to run in
parallel (0 == All) – Use this option to
specify the number of backup jobs
that can be run concurrently. With the default value of zero all the jobs will be
concurrent, limited only by the availability of resources (e.g., library drives,
network bandwidth, etc.). To achieve the desired result, you must set the
same value for each job.