Hub/Switch Installation Guide

Chapter 7 HPSS User Interface Configuration
HPSS Installation Guide September 2002 453
Release 4.5, Revision 2
MaxStagesspecifiesthe maximumnumberofdataeventprocessesthatcan concurrentlystagefiles
from HPSS to Episode. When this limit is reached, further transfers from HPSS are deferred until
one ofthestagescompletes. Thisvalue mustbe less than NumDataProcesses. Avalueinthe range
1-3 is a good starting point.
MaxTcpConnects specifics the maximum number of simultaneous requests to mirrored filesets
managed by this HDM allowed through the HPSS interface. If the value for this parameter is too
small, an HPSS user request may occasionally fail. A good starting value is 200.
MinArchiveMigrationSize defines the minimum file size that will be migrated into an archived
fileset. If the migration process is taking too much CPU time, use this parameter to prevent small
files from being migrated.
MsgFileDirectory specifies the path name of the directory where HDM error message files are
located. Typically, this will be /var/hpss/hdm/hdm<id>. The log files will be named
hdm_message.0, hdm_message.1, etc. The number of these files is controlled by
NumMessageFiles. If MsgFileDirectory is left blank, the HDM will not write messages to the
message files. In this situation, the stdout flag should be defined so that messages appear
somewhere. But remember that using the stdout flag is discouraged, so it is better to provide a
value for MsgFileDirectory.
NumAdminProcesses specifies the number of HDM subprocesses that will be assigned to handle
administration events, such as mounting and unmounting file systems. The value, 2, is a good
starting point.
NumDataProcesses specifies the number of HDM subprocesses that will be assigned to handle
events involving data requests, mainly read and write events. The value selected must be large
enough to allow a reasonable amount of I/O overlap. Remember that, at any given time, some
number of these processes may be busy staging data from HPSS (MaxStages). The value, 8, is a
good starting point.
NumMessageFiles specifiesthenumber offiles thatHDM will use towriteerror messages. Unlike
theotherparameters, thisparameteris optional.Ifitis not supplied,errormessageswill bewritten
to two files. Message files will appear in the directory named by MsgFileDirectory, and the files
will be named hdm_message.0, hdm_message.1, hdm_message.2, etc.
NumNamespProcesses specifiesthe numberofHDM subprocessesthat will beassigned tohandle
eventsinvolvingchangestothenamespace.Theseeventsincludefilecreates,deletes,renames,and
permission changes. The value, 8, is a good starting point.
RegisterBitmap is a 64-bit number, expressed in the form "<high>.<low>", where <high> and
<low> are integers providing the high and low 32 bits of the number. This field is not currently
used, and should be set to 0.0.
SharedMemoryKey is an integer that defines a key used by HDM subprocesses to attach to the
sharedmemory segment initializedby the mainprocess.The key isalso used toidentify the HDM
semaphoreset.Ifavalueofzeroislistedinthefile,adefaultkeywiththevalue,3789,issubstituted.
If onlyone HDMis running ona machine, use zero for thisparameter; this ensures that HDM and
hdm_admin use the same key. The default setting can be changed with the environment variable,
HPSS_HDM_SHMEM_KEY.