Chapter 2 HPSS Planning
98 September 2002 HPSS Installation Guide
Release 4.5, Revision 2
2.9.1.10 PV Estimated Size / PV Size Selection
Guideline:Fortape, select a value that represents how much space can be expected to be written to
a physical volume in this storage class with hardware data compression factored in.
Explanation:The Storage Server will fill the tape regardless of the value indicated. Setting this value
differently between tapes can result in one tape being favored for allocation over another.
Rule1: For disk, the PV Size value must be the exact number of bytes available on the PV.This value
mustbe a multiple of the media block size and the VV block size. The SSM will enforce these rules
when the screen fields are filled in.
Rule2: For disk, the PV Size value must be less than or equal to the Bytes on Device value described
in section 6.9: Configure MVR Devices and PVL Drives (page 401).
2.9.1.11 Optimum Access Size Selection
Guideline: Generally, a good value for Optimum Access Size is the Stripe Length.
Explanation:This field is advisory in nature in the current HPSS release. In the future, it may be used
to determine buffer sizes. Generally, a good value for this field is the Stripe Length; however, in
certain cases, it may be better to use a buffer that is an integral multiple of the Stripe Length. The
simplest thing at the present time is to set this field to the Stripe Length. It can be changed in the
future without complication.
2.9.1.12 Some Recommended Parameter Values for Supported Storage Media
SectionTable 2-3: Suggested Block Sizes for Disk on page 98 and Section Table2-4: Suggested Block Sizes
for Tape on page 99 contain suggested values for storage resource attributes based on the type of
storage media. The specified values are not theonly acceptable values, but represent reasonable
settings for the various media types. See Section 2.8.6 for more information about setting the
storage characteristics.
2.9.1.12.1 Disk Media Parameters
Table 2-3 contains attributes settings for the supported disk storage media types.
Table 2-3 Suggested Block Sizes for Disk
Disk Type Media Block
Size Minimum
Access Size
Minimum
Virtual Volume
Block Size Notes
SCSI Attached 4 KB 0 1 MB 1
SSA Attached 4 KB 0 1 MB 1