Which Rotation Type To Select; Full Data Recovery Period; Access To Historical Files - HP BB118BV - StorageWorks Data Protector Express Package User Manual

Fixed by day of month. An example of an hourly media set is "9:00 PM Hour." An example of a daily
st st
media set is "1 Day of the Month." An example of a weekly media set is "1 Week of the Month." An
example of a monthly media set is "1st Month." An example of a yearly media set is "Yearly 1."
Fixed by day of year. An example of an hourly media set is "9:00 PM Hour." An example of a daily
st
media set is "Day 1 of the Year." An example of a weekly media set is "1 Week of the Month." An
example of a monthly media set is "1st Month." An example of a yearly media set is "Yearly 1."
Each of these media rotations either relies on a predefined set count as described or makes use of the set
count in the interval. To change the interval's set count select the interval and enter the number of sets
you want to keep in the Number of rotation sets field. When a rotation runs out of sets it starts again at
set one and overwrites the media for set one.
Since a set may span multiple media you should not assume that a set is equal to a single piece of media.
Generally you should multiply the number of media sets by the number of pieces of media that a single
backup job uses in order to know how many pieces of media you should have. For example, if your
backup normally takes three pieces of media—and you want two sets of this media—you should have six
pieces of media.
When a rotation is written to media and needs to know the set number it should use for the media's
name it pulls this information from the Next set to use field in the interval. If a backup failed to run
correctly or if for some reason the set numbers are now out of synch you can use this value to change the
name used the next time that interval is run.

Which Rotation Type to Select

Besides the No media rotation option, Data Protector Express provides several default media rotation
types. The rotation types vary in several ways: the number of days for which full data recovery is
available, access to historical files based on backup type (full, differential, incremental, etc.), the
minimum number of tapes or other media needed, and how long media is retained.
All the media rotation types provide for full data recovery in case of disaster. The full data recovery
period is the number of days prior to the data loss for which every file backed up can be recovered. You
will also be able to reconstruct the data for any day during that period that you ran a full backup and for
which a set is available that has not been reused.
Each media rotation type provides full data recovery periods for different number of days preceding the
last backup. For example, a GFS 30-tape media rotation type can reconstruct the data from any day of the
past three weeks (except weekends), while a Simple 4-tape media rotation type provides for
reconstruction of only the past two days. See Comparing rotation types for more information.
To facilitate disaster recovery operations, Data Protector Express provides an optional disaster
recovery agent.
Rotation types vary according to how much access to historical files they provide. Historical files provide
a record of the data stored on the computer or network at particular times such as the end of the week or
the end of the month.