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The two components of NVC, backhitch reduction and data set packing, provide major performance and capacity improvements over standard tape drives, such as the 3590, or the Linear Tape-Open (LTO) writing of synchronized data. Data set packing improves overall tape capacity. Backhitch reduction decreases the frequency of mechanical repositions. NVC provides an innovative approach to increasing capacity and write performance in a way that is not apparent to host applications. 

## 2.1.4 Performance or capacity scaling 

The 3592 tape drives support scaling and segmentation modes on the read/write (JA, JB, JC, JD, or JE) cartridges so that clients can trade-off capacity for improved access times. 

Note:  The TS 1160 drive models supports capacity scaling only on the JE and JD full-length R/W media. Capacity scaling is not supported for economy (JJ, JK, JL, and JM) or Write Once Read Many (WORM) tapes (JW, JX, JY, JR, and JZ). 

Although 256 settings of capacity are supported on the 3592 drive, the following settings are often used: 

GLYPH<SM590000> Full capacity default mode 

GLYPH<SM590000> A 20% scaled fast access mode (capacity scaled, front of tape through an x’35’ setting) 

GLYPH<SM590000> Performance scaling for 87% capacity (segmented format, capacity scaling setting x’E0’) 

Performance scaling, which is also known as capacity scaling , is a function through which data can be contained in a specified fraction of the tape, which yields faster locate and read times. This function is possible through the action of modifying internal formatting indicators in the medium and in the cartridge memory chip. 

The normal serpentine track format is altered in such a way as to limit the recorded portion of the tape to a specified fraction of the length of the tape, as shown in Figure 2-2. In the 3592, an application can issue a Mode Select command to scale an individual cartridge. It pertains only to the cartridge that is loaded and it is not persistent. 

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The result of performance scaling a tape to a percentage value (for example, 20%) is that the maximum number of recordable gigabytes is reduced to 20% of the normal value. Also, the average time to locate a random record on a full tape that starts from load point is (roughly) 20% of the time to locate a random record from load point for a full, unscaled tape. 

The cartridge can be rescaled from any current value to any supported new value. Tape is logically erased by this rescaling. (The end of the data mark is written at the beginning of the tape.) However, tape is not physically erased as with the long erase  command. 

