concurrently written in sess_7 and the second one in sess_8. Note that one object can be stretched over several media. The media usage policy is appendable.
Figure 44 Each object written on a separate medium
Figure 44 on page 150 shows an example of using one backup specification per object with the
For more information on how full and incremental backup policies influence restore performance and media usage, see “Full and incremental backups” on page 71.
Writing data to several media sets during backup
During a backup session, you can write all or some objects to several media sets simultaneously, using the Data Protector object mirror functionality. For more information, see “Object mirroring” on page 119.
Calculating media condition
Media condition factors
Data Protector calculates the state of used media using media condition factors. The state of the poorest medium in a pool determines the state of the entire pool. For example, as soon as the state of one medium in a media pool is poor, the state of the pool becomes poor. When that particular medium is removed from the pool, the state reverts to either fair or good.
Media can have three states: good, fair, or poor.
On a per medium basis, the following is used for calculating the condition:
•number of overwrites
The usage of a medium is defined as the number of overwrites from the beginning of the medium. Once the medium has more than the threshold number of overwrites, it is marked as poor
150 | Media management and devices |