The 3592 Model E05 supports performance scaling and performance segmentation of media tape cartridges. These functions allow you to optimize performance for MEDIA5 and MEDIA9 cartridges; a cartridge can be defined for performance scaling or performance segmentation, but not both.

Performance scaling, also known as capacity scaling, is a function that allows you to contain data in a specified fraction of the tape, yielding faster locate and read times. Performance scaling for the 3592 Model E05 limits the data written to the first 20% (the optimally scaled performance capacity) of the cartridge. To select performance scaling for a cartridge, do these steps:

1. Define a data class that requests performance scaling.
2. Modify or create ACS routines to associate the tape output functions using performance scaling with a data class that requests performance scaling.

The 3592 Model E05 tape drive also divides the tape into longitudinal segments. Using this capability, it is possible to segment the tape into two segments, one as a fast access segment to be filled first, and the other as additional capacity to be filled after. If you decide to use the performance segmentation attribute, do these steps:

1. Define a data class that requests performance segmentation.
2. Modify or create ACS routines to associate the tape output functions using performance segmentation with a data class that requests performance segmentation.

Performance segmentation can also be used with the 3592 Model J1A with MEDIA5, as can performance scaling.

With the 3592 Model E05 and EFMT2, the MEDIA5 cartridge can be segmented into a 100 GB fast access segment and a 333 GB slower access. With the 3592 Model J1A and EFMT1 (or the 3592 Model E05 and EFMT1), the MEDIA5 cartridge can be segmented into a 60 GB fast access segment and a 200 GB slower access segment. The segmented capacities of the extended length cartridge, MEDIA9, is 700 GB.

With a segmented cartridge still having only one physical partition and one EOV indicator, data can only be written to the slower access segment after the fast access segment has been filled. Once the fast access segment has been filled, any data written will continue into the slower access segment. However, if an application wishes to manage what data is placed in which segment, the application will need to manually track and fill the fast access segment before it can place less frequently accessed data in the slower access segment. IBM application control and management of what data is placed in which segment is not being addressed with this support.

The segmentation format may be of benefit if the amount of data written to a tape cartridge is typically between the economy and longer-length cartridge capacities, with data written in the first segment having faster access times. Additionally, for customers that tend to utilize the full capacity of the cartridge, the segmentation format can be used to maximize performance benefits. Otherwise, with the native format using all of the tape cartridge's wraps, performance degradation can occur when data is written to the last few wraps of the tape.