IBM RELEASE 7.3 - Manual (Page 166)

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 given 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 displayed 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 Subsystem Thresholds
These windows allow the user to manage storage class space thresholds which are specific 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 selected 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 storage
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 Information
Section 4.2.3.8: Storage Class Threshold Overrides on page 81.
6.1.4.1. Disk Storage Subsystem-Specific Thresholds
HPSS Management Guide November 2009
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