Hub/Switch Installation Guide

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: For tape, select a value that representshowmuchspacecanbeexpectedtobewrittento
a physical volume in this storage class with hardware data compression factored in.
Explanation:The StorageServerwill fillthetape regardlessof thevalueindicated. Settingthisvalue
differently between tapes can result in one tape being favored for allocation over another.
Rule1:Fordisk,thePVSizevaluemustbetheexactnumberofbytesavailableonthePV.Thisvalue
must bea multipleof the media block sizeand the VV block size.The SSMwill enforce these rules
when the screen fields are filled in.
Rule2:Fordisk,thePVSizevalue mustbelessthanorequaltotheBytesonDevice valuedescribed
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:ThisfieldisadvisoryinnatureinthecurrentHPSSrelease.Inthefuture,itmaybeused
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
SectionTable2-3:SuggestedBlockSizesforDiskonpage98andSectionTable2-4:SuggestedBlockSizes
for Tape on page 99 contain suggested values for storage resource attributes based on the type of
storage media. The specified values are not the only 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