If the tape media supports "fast locate", and that feature is enabled  for the tape devices, choose larger 
values of Seconds Between Tape Marks (SBTM).  When reading from the middle of a file on  tape, the 
fast locate feature is used by HPSS to locate the data block in which a give n portion of a file is located, 
rather than skipping tape marks and data blocks.  When fast locate is enabled, there  is no advantage to 
using smaller values of Seconds Between Tape Marks (SBTM) for locating positions  within files.  The 
fast locate feature is also know as Logical Block Addressing (LBA).
Blocks Between Tape Marks (BBTM). The maximum number of data blocks (of Media Block Size  
(MBS)) that will be written on a tape between consecutive tape marks.
The number of media data blocks between tape marks is calculated by SSM when the Device I/O Rate 
(DIOR) and Seconds Between Tape Marks (SBTM) are set. This value is displ ayed for information 
only. 
The recording space between tape marks is called a “section”. The PV Section  Length is Blocks 
Between Tape Marks (BBTM) times the Media Block Size (MBS). The  VV Section Length is the PV 
Section Length times the Stripe Width (SW).
6.1.4.  Storage Class Subs ystem ThresholdsThese windows allow the user to manage storage class space thresholds which are specif ic to a storage 
subsystem. These windows are accessible only from the Configured Storage Classes window. The  user 
must first select a storage class from the storage classes list. The selecte d storage class will be referred to 
as the ‘parent’  storage class to the subsystem threshold window which is opened when the  storage class 
is selected.
Each Storage Class Configuration window has fields for Warning Threshold and Critical  Threshold. 
By default, these thresholds apply to all storage subsystems using the storage class. However, the st orage 
class thresholds can be overridden by configuring a subsystem-specific threshold allowing a storage 
subsystem to have its own customized set of Warning Threshold and Critical Threshold values. 
After creating or modifying any thresholds, the Core Server and Migration Purge Server for the affected  
subsystem must be recycled to make the changes effective.
Related Informatio n
Section 4.2.3.8: Storage Class Threshold Overrides on page 81.
6.1.4.1.  Disk Storage Sub system-Specific Thresho ldsHPSS Management Guide November 2009
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