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Chapter 2 HPSS Planning
HPSS Installation Guide September 2002 123
Release 4.5, Revision 2
Table 2-6 HPSS Dynamic Variables (Subsystem Specific)
Variable Description
Max Total Bitfiles The maximum number of bitfiles that will exist in HPSS. The spreadsheet also
considers this value to also be the total number of bitfiles on tape, since it is assumed
that every HPSS bitfile will eventually migrate to tape. If it is expected for 2 million
files to be placed in HPSS, enter 2,000,000. This value significantly impacts the overall
metadata sizing estimate.
Max Bitfiles on Disk Used to determine how many bitfiles might reside on disk at any point in time. This
number must be less than or equal to Max Total Bitfiles. For example, if disk space is
sufficient to hold/cache 20,000 of the 2 million total files, enter 20,000. This value
significantly impacts the overall metadata sizing estimate.
Avg. Copies Per
Bitfile
Defines the average number of copies per bitfile (since HPSS supports duplicate bitfile
copies). For example, if there is approximately 1 extra bitfile copy for every 100 bitfiles
created, enter a value of 1.01. This value significantly impacts the overall metadata
sizing estimate. If not using duplicate bitfile copies, use a value of 1.0.
Percent of Extra
Copies Stored on
Tape
When duplicate bitfile copies are created, the extra copy(s) are written to a lower level
in the storage hierarchy. Usually, lower levels are defined as tape storage classes. Enter
the average percentage of these extra bitfile copies that will be stored on tape (versus
another disk storage class). This value significantly impacts the overall metadata sizing
estimate if the duplicate copy feature is used.
Max Accounting
Log Records
This value is the maximum number of log records that is expected at any given time
when the BFS is updating the (acctsum) file. The number of records will depend upon
system load, but should typically not exceed 3000.
Avg. Name Space
Objects Per Bitfile
One name-space object is created for each HPSS bitfile; however, other name space
objects, such as directories and links, are also created. This value defines, on average,
how many name space entries there are per HPSS bitfile. For example, if there is one
additional name-space object created for each 20 bitfiles (directory or link) on average,
a value of 1.05 would be entered. This value significantly impacts the overall metadata
sizing estimate.
Avg. Object ACL
Entries Per Name
Space Object
A name-space object record can store up to 4 Object ACL entries (in addition to the
user_obj, group_obj, and other_obj ACL entries). If an object has more than four
Object ACL entries, an ACL record must be created. Each ACL record can hold up to
16 ACL entries. This value defines, on average, how many ACL records will be created
per name-space object. For example, if 1 in 100 name-space objects will have between
5 and 20 ACL entries, a value of .01 would be entered.
Avg. Initial
Container and
Initial Object ACL
Entries Per Name
Space Directory
Object
If Initial Container (IC) and/or Initial Object (IO) ACL entries are used, at least one
ACL record will be created for each type of ACL. Each ACL record can hold up to 16
ACL entries. This value defines, on average, how many IC/IO ACL records will be
created per name-space directory object. For example, if 5 in 100 name-space objects
will have between 1 and 16 IC/IO ACL entries, a value of .1 would be entered.