Hub/Switch Installation Guide

Chapter 2 HPSS Planning
106 September 2002 HPSS Installation Guide
Release 4.5, Revision 2
2.10.1 HPSS Storage Space
HPSS filesare stored on themedia that isdefined to HPSS viathe import andcreate storageserver
resources mechanisms provided by the Storage System Manager. You must provide enough
physical storage to meet the demands of your user environment. HPSS assists you in determining
the amount of space needed by providing SSM screens with information on total space and used
space in all of the storage classes that you have defined. In addition, alarms can be generated
automatically based on configurable threshold values to indicate when space used in a given
storage class has reached some threshold level. In a hierarchy where data is being migrated from
one storage class level to a lower one, management of space in the storage class provided is done
via themigration and purge policies that youprovide. Thebasic factors involved here are the total
amountofmediaspaceavailableinthestorageclassbeingmigratedandtherateatwhichthisspace
is used. This will drive how the migration and purge policies are set up for the storage class. For
more details on this, see Sections 2.8.1 and 2.8.2. Failure to have enough storage space to satisfy a
user request results in the user receiving a NO SPACE error. Oneimportant factor in storage space
growthrelatesto howHPSS handleswriterequests.The BitfileServeralways writesdatato thetop
level in the hierarchy. When the top level is out of space, the Bitfile Server will not attempt to
allocate space in a lower level and write the remaining data to the lower level.
2.10.2 HPSS Metadata Space
During the HPSS planning phase, it is important to properly assess how much disk space will be
required to support the HPSS production environment. The first step in this process is to
understand the various metadata files managed by each HPSS server. The sections that follow
explainthemetadatafilesusedbyeachHPSSserverandprovidehintsonhowtobestestimatehow
many records will be in each file. The second step in the process is to use the metadata sizing
spreadsheet,explainedinSection 2.10.2.21,whichhelps tocalculatedisk spacerequirementsbased
on various HPSS sizing assumptions.
The naming convention for various SFS files has changed to accommodate this addition. All files
suffixed with a “.#” are associated with a subsystem instance ranging from 1 to n. All remaining
SFS files are uniquely named and therefore do not have a suffix. The following list of files are
considered part of a subsystem:
acctlog.#
bfcoschange.#
bfdiskallocrec.#
bfdisksegment.#
bfmigrrec.#
bfpurgerec.#
bfsssegchkpt.#
bfssunlink.#
bftapesegment.#