The HRTD feature maintains an overall granularity of 64 directory entries per logical wrap.  Consider the following points: 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: 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.  These drives support the  external copy  function, which offers the following advantages:  98  IBM TS4500 R6 Tape Library Guide GLYPH<SM590000> The function works in a SAN environment, and it is supported on true switches  (non-hubs). 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> Data can be an entire volume or a group of logical blocks.  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> 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. 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 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> 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> 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.  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> JC media 842 m (920.8 yards) logical wrap results in a granularity of 13.2 meters (43.3 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> JA media 570 m (623.36 yards) logical wrap results in a granularity of 8.9 meters (29.1 ft.). Main data buffer External copy support 