Date: MAY 2011
Product & Version: Netvault
OS Version: All supported versions
Module & Version: NDMP plugin
Application version:
Symptoms:
NDMP Filer backups to locally attached tape drives are slow.
Cause / Explanation:
In order to backup data residing in Filers such as NetApp and others, NetVault instructs the filer to use its backup utility to transfer the needed data to the target drive.
For example, the supported backup TYPE for NetApp filers is DUMP.
Other filers would use backup types such as TAR and ZFS...
In the case of NetVault, we instruct the filer to run a DUMP command to backup the needed data to tape.
From that point on the backup is reliant on the filer operating system and the system resources that it allocates to the backup process, such as memory, CPU and disk I/O.
Essentially it is the filer that handles transferring the backup stream to the target drive.
If poor performances are seen during backups, there could be several factors outside of NetVault that influence backup speed:
- media block size not at its optimal value
- filer operating system allocation of resource to the backup process
- the filer's ability to access data and copy it using its DUMP program to tape
- Try different Block sizes until you find the block size with the optimum transfer rate.
Note: Ensure tapes used are blanked after changing block sizes on the tape drives.
- Speak to Filer operating system support to diagnose why the backup is receiving insufficient resource or why the I/O from the disk is slow.
