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If the MOVEBATCHSIZE or MOVESIZETHRESH parameters are increased from
the default values, the server will require more recovery log space—up to two or
more times larger than a recovery log when the defaults are used. Also, the
server requires more time to initialize at startup. The impact of a larger recovery
log size will be felt while running the server with the logmode set to NORMAL
(the default value). If you choose to increase these values for performance
reasons, be sure to monitor recovery log usage during the first few storage pool
backup/restore, migration, reclamation, or move data executions to ensure
sufficient recovery log space is available.
Tip: Tivoli Storage Manager can be configured to auto-configure and monitor
these parameters, so that it can increase its ranges for better throughput.
When the SELFTUNETXNSIZE parameter is set to YES in the server options
file, the MOVEBATCHSIZE and MOVESIZETHRESH server options will both
be set to their maximum possible values to optimize server throughput. Also,
the server will monitor and change the value of TXNGROUPMAX to optimize
client-server throughput.
Recovery log
If you use the TXNGROUPMAX and TXNBYTELIMIT parameters, remember
that larger transactions require more recovery log space. The Tivoli Storage
Manager server can require more time when re-starting, to process the log
entries. Again, see "TXNBYTELIMIT" on page 506 for more information about
the transaction process and the side effects on the recovery log.
15.3.3 Communication
This section covers server options that influence the performance and behavior
of communication protocols between client and server.
MAXSESSION
The MAXSESSION parameter specifies the maximum number of simultaneous
client sessions that can connect to the Tivoli Storage Manager server. The
default value is 25 client sessions, and the minimum value is two. The maximum
value is limited only by available virtual memory or communication resources.
This parameter specifies the maximum number of simultaneous client sessions
that can connect to the Tivoli Storage Manager server. By limiting the number of
clients, server performance can be improved, but the availability of Tivoli Storage
Manager services to the clients is reduced.
Since Tivoli Storage Manager clients use multi-threading, you should consider
the total number of concurrent nodes, times the number of concurrent sessions
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IBM Tivoli Storage Manager Implementation Guide
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