An Example Media Rotation; Media Sets - HP BB118BV - StorageWorks Data Protector Express Package User's Manual & Technical Reference

• Media Rotation and Scheduled Backup Jobs
Backup jobs performed for disaster protection are often run daily. Ensuring that you have all the files you
need to restore your system often involves creating and maintaining one or more sets of media (such
as tape cartridges) for use during a recovery. Rather than use new media each time a backup job is
run, Data Protector Express recycles or reuses media. This is efficient because it keeps costs down by
limiting the amount of media needed and still provides for data security, should any media fail or be
otherwise unavailable.
The process of recycling or reusing media is referred to as media rotation.Data Protector Express contains
several default media schedules with default media rotations. We recommend you use one of these
defaults whenever possible.
Data Protector Express rotates media by creating media sets named to correspond to a job's scheduled
backup intervals, and reuses media using a fixed number of sets. The media set names can be based
either on the scheduled interval or on the type of fixed rotation.
When two intervals in a schedule are scheduled to run at the same time, they have the following
precedence: Year, Month, Week, Day, Hour, Minute. For example, if a job was scheduled to run every
hour using the Hour interval, and once every day using the Day interval—then once each day the daily
backup would take precedence over the hourly backup.

An Example Media Rotation

Many users use what is called the "Grandfather, father, son" media rotation concept. In our example
schedules these are marked by using the acronym "GFS." In a GFS rotation you use progressively larger
intervals with fuller backups. The GFS-20 schedule uses a total of 20 sets. Six sets are used for the Day
backup interval. Six sets are used for the Week backup interval. Six sets are used for the Month backup
interval. Two sets are used for the Year interval.
Using this GFS-20 schedule, the first media set used would be "Yearly Set 1" since all the time intervals
would try to run as soon as they were scheduled to, and the Year interval would have precedence
over all of the other intervals.
NOTE:
You can also create a job in Data Protector Express that does not contain any media rotation. If you do so,
Data Protector Express will not prompt you to insert specific media in a backup device; instead you are
responsible for reusing media based on your own media rotation plan. To avoid overusing your media,
and for maximum data availability when rotating media manually, be sure you always use the oldest
backup media each time you run the backup job.

Media Sets

Data Protector Express organizes rotated media into groups and sets based on the rotation type and
schedule interval. You can use these sets of media to recover data in the event of a disaster or other
data loss. Data Protector Express tracks which versions of files are stored on any set of media to ensure
successful data recovery.
Each time you run a backup job, Data Protector Express copies data onto backup media. Data Protector
Express organizes the media used to complete a single backup job into distinct media sets. Whether
the job requires several media or only one media to complete, they are identified in the Data Protector
Express catalog as a set. If you need to restore a specific version of a file, Data Protector Express will
locate the data based on its media set.
When planning scheduled backup jobs, it is important to know whether one media or several will be
required to complete a backup job. This can usually be estimated by comparing the size of the backup
selection to the capacity of the selected media. If you do not want Data Protector Express to use more
than one media for a backup job, then you must select fewer files to back up.
For fixed rotation types, Data Protector Express will select media sets based on the day of the week, week
of the month, day of the month or day of the year. Data Protector Express assigns names to media
sets in a fixed rotation using the schedule below.
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Backup Jobs