Title: Slow duplication transfer to physical tape drive
Date: 19/02/2007
NV Version: All
OS Version: All
Description: This FAQ describes performance issues during Duplication from VDL to physical tape drive.
Symptoms:
When using a physical tape library connected directly via SCSI to the NetVault server, the duplication phase can some time be very slow.
Typically the Phase 1 is done on VDL then the phase 2 on LTO drive, although no network traffic is involved the transfer rate is very low: 1 Mb/s
This generally can be due to incorrect settings for the drive performance configuration. To verify these settings:
- go to NetVault Device Management,
- right click on the LTO drive
- select 'Configure'
- go to the 'Performance' tab
- Change the value for the option: 'Amount of memory to assign for transfer buffers (Kb)'from the default 257 to 65537 (64MB).
This value represents the amount of buffer space that is to be shared between the two transfer functions, and is allocated in blocks of 32 Kb.
The default value of 257 Kb must be increased to a large value so that a large amount of buffer space is created through the use of system memory
and can be used by a NetVault job in order to speed up the overall process. The transfer buffer space has a huge impact on the performance of a backup job.
For more information on this subject refer to the administator's guide.
SFDC solution number:
Version française disponible ID 00002092
Deutsche Version verfügbar ID
