Dell PowerVault DR6000 - Manual (Page 32)

32 Setting up NetVault Backup Native Virtual Tape Library on the Dell™ DR4X00 Disk Backup Appliance
The DR4x00 units are capable of running a cleaning cycle on a regular basis to recover data space that is
no longer required by the deduplication process.
Using a DR4x00 unit as a NVBU VTL repository will require periodic maintenance to achieve the best
usage from the DR4x00 unit.
Space reclamation from virtual media of a NVBU VTL hosted on the DR4x00 has some specific
requirements. Even though NVBU can locate and blank media that is marked for reuse, the DR4x00 unit
will not know that NVBU has marked the media for reuse and will not reclaim the space on the next clean
cycle. This is due to the fact that NVBU will only update the header on the media and not scrub through
and remove the old data.
To ensure that the DR4x00 clean cycle can reclaim space, the marked for reuse media must be identified,
blanked using the nvmakemedia utility removed and then re-added as a new file. Since the new file no
longer has any content, the DR4x00 clean cycle can reclaim the space. A script can be run to build a list
of the media, blank it, and use the nvmakemedia utility to recreate the files. Refer to Appendix D for an
example script that can be modified for either type of installation.
5.2 NetVault: Backup Optional Configurations for Optimum
Performance
Please follow the below steps to ensure optimum performance settings.
1. Within the Device Management window right click on each Select the Configure tab. Select the drive
and right-click. Select Configure, to display the Configure Device window.
2. In the Configuration tab, increase the Media Block Size (KB) from the default setting of 32 KB. Ensure
the operating system and drive can support the new value entered.
3. In the Performance tab, increase the default Transfer Memory Buffer setting from the default setting
of 257 KB. Ensure the operating system can support the new value entered.
4. Important: The amount of memory to assign to transfer buffers (KB) is what is often referred to as the
shared memory setting. The shared memory is allocated in 32 KB blocks with one additional byte. The
optimum figure is dependent on the drive model, but the minimum value to use is at least 4x the block
size setting for the drive. Ensure there is sufficient RAM (Windows) or Kernel Memory (UNIX). Use
more shared memory if available and as required.
5. Repeat steps 1 – 3 for each drive as required.
6. Save device configuration by clicking the Save Details button in the top left corner.