The HRTD feature maintains an overall granularity of 64 directory entries per logical wrap. Consider the following points: 

GLYPH<SM590000> JA media 570 m (623.36 yards) logical wrap results in a granularity of 8.9 meters (29.1 ft.). 

GLYPH<SM590000> JB media 775 m (847.55 yards) logical wrap results in a granularity of 12.1 meters (39.6 ft.). 

GLYPH<SM590000> JC media 842 m (920.8 yards) logical wrap results in a granularity of 13.2 meters (43.3 ft.). 

GLYPH<SM590000> JD media 1032m (1128.6 yards) logical wrap results in a granularity of 8.06 meters (26.4 ft.). Granularity is improved for the segmented or scaled formats with shorter logical wraps. 

GLYPH<SM590000> JE media 1088m (1190 yards) logical wrap results in a granularity of 8.06 meters (26.4 ft.). For the segmented or scaled formats with shorter logical wraps, granularity is improved. 

The 3592 drive has many redundancy and recovery features that prevent the possibility of data loss in the loss of a directory. It also allows a rebuild of the directory under all circumstances. consider the following points: 

GLYPH<SM590000> The HRTD table consists of information for each logical wrap. Each wrap area contains up to 64 entries. Each entry contains the LPOS, logical block, and file mark count information with access point and other internal information of interest. 

GLYPH<SM590000> The entire HRTD table is stored in the housekeeping data set on tape. The entire HRTD structure is also written in the end-of-data (EOD) data set for the tape if the tape has a valid EOD. The HRTD entries are also distributed in accumulating sequential fashion into the Data Set Information Table of all user data sets as they are written on tape. Control structures, which define the validity of the HRTD and EOD information on the tape, are in the cartridge memory. 

GLYPH<SM590000> If a valid HRTD cannot be recovered from the housekeeping data set, the HRTD might be rebuilt by using the EOD or distributed copies of HRTD information. The HRTD can also be rebuilt by reading the tape. Depending on the mechanism that must be used to rebuild the HRTD, this rebuild occurs quickly (seconds if the EOD copy can be used) or take longer (minutes if a full rebuild is required). 

GLYPH<SM590000> The drive can read all data from a cartridge without any HRTD information, although locate times might be affected. However, the drive does not allow a write operation without a valid HRTD to guarantee the integrity and validity of the information on tape. 

## Main data buffer 

These drives feature the same 2 GB main data buffer as the TS1155, which is twice the size of the 1 GB main buffer in the TS1140 drive. The extra buffer is used to improve overall performance, reduce backhitches, improve speed matching performance, and support BOP caching and other improvements. 

## External copy support 

These drives support the external copy  function, which offers the following advantages: 

GLYPH<SM590000> The capability is similar to serverless copy in that it allows data to be copied from one drive to another drive with no transfer through the host at high data rates. 

GLYPH<SM590000> Data can be an entire volume or a group of logical blocks. 

GLYPH<SM590000> The hosting drive (TS1160 or any drive that supports the feature) can pull or push data to a second drive of any type (vendor-neutral and does not require feature support). 

GLYPH<SM590000> The function works in a SAN environment, and it is supported on true switches (non-hubs). 

