Future Data Growth; Considerations For Copies - HP StorageWorks 12000 - Virtual Library System EVA Gateway Manual

to optimize retention times of the VLS or D2D? Retention policies help you recycle virtual media. Bear
the following considerations in mind as you plan retention policies:
• If you are not using deduplication, you can retain the data on the disk backup device for a shorter
period such as 1-2 weeks (because more than 90% of restores generally occur within the first
week's retention of backups) and then use tape copies to retain data for longer periods.
• If you are using deduplication, you can retain data on your disk backup device with the same
level of retention times as you would have had on tape. This provides a more granular set of re-
covery points with a greater likelihood that a file that you need to recover will be available for
longer and in many more versions. To use deduplication-enabled replication you must have at
least two full backups retained on the disk backup device.
• Once the retention period expires, the virtual media is automatically recycled.
• You should set the tape expiration dates (that is, when the tape is marked as worn out) high because
virtual media does not wear out.
• Backup-job retention time is for virtual media.
• Copy-job retention time is for physical media.
• When copying through the backup application, the virtual and physical pieces of media are
tracked separately and the retention times should be considered and set individually.

Future Data Growth

How fast is your data growing? This is critical in deciding which disk backup technology best fits;
choose a technology that will continue to scale in performance and capacity so that it still can provide
a single backup target even after several years of data growth.
If you choose a disk backup technology that starts close to it maximum performance/capacity, then
as data grows you must add another device (and thus another backup target) and so on, which means
significant increases in backup administration over time due to having to manually balance all backup
jobs across multiple backup targets. This manual balancing is even more difficult when you have
multiple targets that are each separate deduplication domains, because then when you switch a
backup job from one target to another it "resets" the deduplication for that backup making capacity
planning very complex.

Considerations for Copies

Generally the disk backup device is located at the same site as the data being backed up, which
means you must create copies of the backup data that are stored in a different remote site to protect
against a site disaster. There are also sometimes long-term (e.g., multi-year) retention requirements
for some backup data that may require copying the backups to physical tape. (There may be legal
requirements to use tape, plus a tape on a shelf uses zero power compared to storing the long-term
retention backup data on spinning disks). When designing your solution, consider the following
options available for copying backups. You can implement all of these without affecting the application
servers and with the minimum of impact on data center backup processes.
• Copy your backups from your virtual library to physical tape and then ship these physical tapes
to off-site storage. There are different methods of creating the copy on physical tape:
• Use the backup application to copy data from the virtual library to the physical library (preferred
method).
• Use the automigration functionality within the VLS (which turns the VLS into a disk-cache of the
physical library) or the tape offload functionality within the D2D.
• If you are using deduplication, another option is to use the deduplication enabled replication
technology which cost-effectively copies the backups to another remote device (e.g., VLS replicates
38 Backup Solution Design Considerations