HP B6960-90078 manual Device Properties Dialog Box Concurrency, Segment Size

Configuring and Using Backup Devices

Device Concurrency, Segment Size, and Block Size

Figure 2-14 Device Properties Dialog Box: Concurrency

Changing	Segment size is related to the size of data areas which Data Protector
Segment Size	uses in writing data to the media. It is user-configurable for each device.
	Note that a smaller segment size consumes media space because each
	segment has a file mark which takes up space on a medium. A larger
	number of file marks results in faster restores, because the Media Agent
	can quickly locate the segment containing the data to be restored.
	Optimal segment size depends on the media type used in the device and
	the kind of data to be backed up. The average number of segments per
	tape is 50. The default segment size can be calculated by dividing the
	native capacity of a tape by 50. The maximum catalog size is limited to a
	fixed number (12 MB) for all media types.
	Data Protector finishes a segment when the first limit is reached. When
	backing up a large number of small files, the media catalog limit is
	reached faster, which can result in smaller segment sizes.

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