HP BB118BV - StorageWorks Data Protector Express Package, User Manual, Page: 177 / 365

Chapter 11: Managing Devices and Media 159
This rotation type is universally available and by no means unique to Data Protector Express. GFS-30
provides 30 media sets. Note that a set may actually equate to one or more physical cartridges—if it is
necessary to span cartridges during a backup session, Data Protector Express does this automatically.
Look at Interval Settings . This rotation type makes 12 sets available for daily backups, 8 sets for weekly
backup, 8 sets for monthly backup and 2 sets for yearly backup. What this means is that daily backup
cartridges are effectively retained for two weeks before they are overwritten; weekly backups are retained
for 2 months before they are overwritten, and so on. Simply click the cursor in a date in the calendar;
information about the set to which it belongs is shown in the information text below the calendar. Note
that daily backups always default to incremental and weekly, monthly and yearly default to full,
(regardless of any settings you made to the Backup and Write modes in the Job Options step of the
wizard).
If this retention policy is over-cautious for your needs, simply select Custom as the Rotation type to
make the GFS-30 model editable. You can then change the number of sets and edit the write mode, if
required, by clicking on the appropriate interval button.
Rotation types are described in more detail earlier in this guide (page ref?).
Media guidelines
When you run the job for the first time, Data Protector Express looks for blank media and names it
according to the rotation type selected and its position within a set.
•
Do not format media that you wish to use for a rotation schedule; Data Protector Express will be
unable to use it for the backup job because media is automatically named and tracked according to its
position within the rotation cycle (Daily Set 1, Daily Set 2, and so on).
•
If a piece of media is removed or the catalog record is corrupted, Data Protector Express will prompt
you to load the media during subsequent backups. If this is not possible, Data Protector Express will
use the next blank cartridge.
A Note About Streaming
A stream is a set of files to be backed up asynchronously to other streams. Data Protector Express
automatically enables multi-streaming within the software, providing up to eight concurrent data streams
per drive (depending on license of the edition) and streaming to multiple devices in parallel.
Streams are assigned to a device in a round robin method. If you have two streams and two devices, Data
Protector Express will use both devices in parallel. Data Protector Express uses self-tuning logic to
determine the most appropriate way of streaming data. For example, if you are backing up a C: and a D:
drive that are both on the same physical disk, a single stream may be more appropriate to prevent disk
thrashing. If the volumes are on separate disks, two streams can be used.
There is no load balancing logic in place to intelligently assign streams based on their data size, but any
zero-byte streams will be grouped with other streams to avoid using media unnecessarily.