In Tivoli Storage Manager (TSM) environment, to increase the client backup and restore process speed three parameters play an important role. The three parameters are MAXSESSIONS, RESOURCEUTILIZATION and MAXNUMMP. In any kind of TSM environment, good client backup/restore speed can be achieved by adjusting these three parameter with appropriate values. To understand the relation between the MAXSESSIONS and RESOURCEUTILIZATION parameters, you need to understand the two terms INBOUND and OUTBOUND.
Also Read: How to configure TSM Client Backup & Archive Schedules ?
A session established between a TSM client and TSM server can be classified as either INBOUND or OUTBOUND. An INBOUND session is one where the client initiated the session (client contacted the server). An OUTBOUND connection is where the server initiates the session (server contacts the client, usually for a scheduled action like a backup).
Also Read: How to configure TSM Client Backup & Archive Schedules ?
A session established between a TSM client and TSM server can be classified as either INBOUND or OUTBOUND. An INBOUND session is one where the client initiated the session (client contacted the server). An OUTBOUND connection is where the server initiates the session (server contacts the client, usually for a scheduled action like a backup).
Relation beween MAXSESSIONS and RESOURCEUTILIZATION
The server option MAXSESSIONS is used to control the number of inbound sessions that can be active at one time. For example, when MAXSESSIONS is 55, this means that only 55 inbound sessions can be active at one time. Because each client can have multiple inbound sessions by adjusting the client option RESOURCEUTILIZATION, you need to carefully determine a proper MAXSESSIONS value.Assume the default value of RESOURCEUTILIZATION 2 is used and 55 clients execute dsmc at one time. MAXSESSIONS should be set to 110 so that all 55 clients can use two sessions when connecting to the server.
The maximum number of outbound sessions that can be active at one time is set by the server command SET MAXSCHEDSESSIONS. The value specified is a percentage of MAXSESSIONS.
For example, when MAXSESSIONS is set to 220 and MAXSCHEDSESSIONS is set to 40(%), then the maximum number of outbound sessions that can be active at one time is 88. This number does not affect the maximum number of inbound sessions.
For example, say MAXSESSIONS is set to 220 and MAXSCHEDSESSIONS is set to 40(%). This means the total number of inbound and outbound sessions is 308, or the sum of 220 + 88 (where 88 is 40% of 220).
Also Read: TSM Server Performance Tuning Parameters
Remember that the sessions established for TSM server administration and TSM server/storage agent to TSM server communications are not counted against the maximum sessions. In the example above, a total of 308 non-admin client inbound and outbound sessions can be active at one time but there is no set number of admin client sessions that can be active at one time.
The conclusion is that the number of sessions that can be active at one time (as shown by the QUERY SESSIONS command) can be larger than the MAXSESSIONS value.
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