Filter
Top Products
79
2. For “Media Copies” it is always best to try and match the D2D VTL cartridge size with the physical media
cartridge size to avoid wastage. For example: if using physical LTO4 drives (800 GB tapes) then when
configuring D2D Virtual Tape Libraries the D2D cartridge size should also be configured to 800 GB.
3. Schedule time for Tape Offloads: The D2D is running many different functions – Backup & Deduplication,
Replication and Housekeeping – and Tape Offload is another task (that involves reading data from the D2D).
To ensure the offload to tape performs the best it can, no other processes should be running. In reality this
means actively planning downtime for tape offloads to occur. Later in this guide there is a complete multi-site
D2D scenario, an extract is shown in the planning schematic below. This example shows a very busy target
D2D which has local backups (green), replication arriving (blue), housekeeping activity (yellow); replication
and housekeeping windows have been assigned to enable predictable performance.
By applying housekeeping windows it is possible to free up spare time on the Target D2D which could then
be used either for future headroom for growth or to schedule tape offloads. These tape offloads would take
place in the grey shaded area, 06:00-12:00 in the above diagram.
4. Offload a little at a time or all at once? Depending on the usage model of the D2D and the amount of data to
be offloaded you may be able to support many hours dedicated to tape offload once per month. Or, if the
D2D is very busy most of the time, you may have to schedule smaller offloads to tape on a more frequent
weekly basis.
5. Importing data? When copying to tape at a D2D target site it is only possible to copy after the backup server
is aware of the replicated data from the source D2D. It is important to walk through this import process and
schedule the import process to occur in advance of the copy process, otherwise the copy process will be
unaware of the data that must be copied. In the case of HP Data Protector specific scripts have been
developed that can poll the target D2D to interrogate newly replicated cartridges and NAS files. HP Data
Protector can then automatically schedule import jobs in the background to import the cartridges/shares so
that when the copy job runs, all is well. For more information go to: HP Data Protector Import scripts.
6. Other backup applications’ methods may vary in this area. For example, for most backup applications the
target D2D can be read only to enable the copy to tape, but Symantec Backup Exec requires write/read
access which involves breaking the replication mappings for this to be possible. Please check with your
backup application provider before relying on the tape offload process or perform a DR offload to tape to
test the end to end solution.