Client And Backup Job Naming - HP 12000 Design Manual

Use the following guidelines:
Appending media pool
HP recommends using standard, appending shared media pools across multiple tapes. By
doing so, tapes fill with backup jobs from different hosts, which allows deduplication to occur
and storage to be reclaimed.
You should not use non-appending media pools.
Virtual cartridge sizing
Generally, it is always better to create smaller cartridges than larger ones because it frees up
the cartridge quicker for use by other processes such as restore, tape copy or deduplication
processing. Cartridge sizes of 100-200 GB are common and this size can be used regardless
of the tape emulation type because the cartridge is virtual (you can create a 100 GB cartridge
even if you selected LTO4 drive emulation).
However, with Accelerated deduplication there are other sizing considerations that could
recommend even smaller cartridge sizes. If the daily amount of backup data written to your
cartridges is significantly less than the cartridge size, the deduplication process will only be
able to eliminate the duplicate data (free up disk space) once the tape has been filled up by
multiple days of backups.
In other words, if your average backup job size is significantly smaller than the virtual cartridge
size:
◦ Divide the number of jobs by the number of virtual tape drives. This determines
approximately how many jobs will write to each cartridge per night and thus how much
logical data is written on average to each virtual cartridge.
Divide this logical data per cartridge by the average data compression ratio to get the
◦
native capacity required.
Compare the native capacity required to the cartridge size. If the native capacity written
◦
per night is less than the cartridge size, reduce the cartridge size to roughly match.
For example, if you have 50 backup jobs per night with an average size of 25 GB each,
writing to 10 virtual tape drives, this writes 125 GB logical data per drive (50/10 * 25).
With 2:1 compression you get 62.5 GB native disk capacity per drive per night. In this case,
use a cartridge size of 50 GB.
The recommended virtual cartridge sizing for most environments is 50- 1 00 GB. You may need
to configure a subset of your cartridges at a larger size if some of your backups are very large
and you want to reduce the number of tapes the backup spans. (Spanning too many tapes
reduces deduplication performance so ensure that cartridge sizing does not have a single
backup span of more than 30 cartridges.) The maximum recommended cartridge size is 300
GB.

Client and Backup Job Naming

Deduplication relies on the names of the backup job and the client to correlate them.
If you rename the backup job or client after you have deduplication running on your system,
the deduplication for that backup data is reset (as though you just activated it for the first time).
Do not divide full backups and incremental backups across different job names. They must
operate under a common backup job name.
If a client is removed from the backup application configuration (for example, the client is
decommissioned or renamed), you must set that client's backup policy/name to Deduplication
96 Accelerated Deduplication