Hub/Switch Installation Guide

Chapter 7 HPSS User Interface Configuration
450 September 2002 HPSS Installation Guide
Release 4.5, Revision 2
The following paragraphs discuss each parameter found in the file. Except as noted, each
parameter must be specified. HDM will not start if a mandatory parameter is omitted. The
configuration parameters can be specified in any order. The keywords must be spelled correctly,
using the specified upper and lower case letters. For example, DescName, not descName or
descname.
AclLogName specifies the name of the file used for the ACL log. Typically, this will be /var/hpss/
hdm/hdm<id>/hdm_acl_log. This file contains a record of pending ACL change requests made
through the HPSS interface. The file must exist before HDM is started, but can be empty. The size
ofthe fileisunbounded,buttypically willbe small.Thislogisveryimportantand shouldbe stored
on a reliable disk.
DestroyLogName specifies thename of the fileused for thedestroy log.Typically, this will be/var/
hpss/hdm/hdm<id>/hdm_destroy_log. This file contains a record of all files on mirrored filesets
that need to be destroyed. The file must exist before HDM is started, but can be empty. If
DestroyLogSize is changed, HDM automatically adjusts the size of the file. This log is very
important and should be stored on a reliable disk.
DestroyLogSize specifies the total number of files in mirrored filesets that are waiting to be
destroyed, thus determining the size of the log file. Because of limitations in DFS SMT, it is not
possible to destroy HPSS files immediately when a destroy event is received. For example, after a
recursiveremove, thenumber of pending filedestroys canbecome quite large.Once the logis full,
attempts to remove file names and delete the file data will be delayed until the destroy process
clearsthe log.Anotherconsiderationoccurswhen auser's programcreatesafile,opens it,and then
unlinks it, expecting that when the program exits, the file will go away. HDM must keep an entry
forthis fileinthe destroyloguntil theuser'sprocessexits. Thisties updestroylogentries. Forthese
reasons, a fairly large DestroyLogSize should be used. On the other hand, avoid using an
excessively large value because that causes more overhead when deleting files. Also, if the system
has aheavilyloadedarchived file system,itmaytake awhile forHDM toget aroundtodestroying
filesonthemirroredfilesystems.UsingasmallerDestroyLogSizetendstofixthisproblem.Agood
startingvalueforDestroyLogSize is 200.Thenameofthis logfileisspecifiedbyDestroyLogName.
If necessary, DestroyLogSize can be decreased by editing config.dat and restarting HDM.
However, this only works if the new value is large enough to accommodate all of the outstanding
entries in the old destroy log.
EventQueueSizespecifiesthemaximumnumberofeventsHDMcanqueueforprocessing.Ideally,
the number should be the sum of NumDataProcesses, NumNamespProcesses, and
NumAdminProcesses, but itmay be a goodidea to use aslightly largernumber. If the value istoo
small, somesubprocesses couldlie idle. Forexample, if the queuehappens to fillwith data events,
then name space processes will lie idle until some of the data events have finished processing. A
value in the range 20-50 is a good starting point.
ExecPath specifies the path name of the directory where HDM executables are located. Typically,
this will be /opt/hpss/bin.
Flags definesspecial flagsthat controlthe operation ofHDM.The parameteris specifiedasa series
of keywords, separated by white space. Currently there are two keywords defined:
"permissiveMount" and "stdout".
When aDFS aggregateis exported and "permissiveMount"is specified, HDMwill check its tables
to see if itmanages that aggregate. If not, itassumes thatsome other HDM manages theaggregate
and relays the event forward. If no other HDMs are prepared to manage the aggregate, it will be
mounted but will not be kept in sync with HPSS. This flag is required when several HDM servers