NonStop Servlets for JavaServer Pages (NSJSP) 6.1 System Administrator's Guide

Configuring NSJSP
NonStop Servlets for JavaServer Pages (NSJSP) 6.1 System Administrator’s Guide—596210-006
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Determining the Storage Capacity of the Persistent
Store
It is possible to set the value of this variable at run time using the modify MBeans
feature of the NSJSP Manager. The value set at run time will take effect
immediately but will not be persisted and will not be available across web
application context restarts.
Determining the Storage Capacity of the Persistent Store
It is important to determine how many sessions may need to be stored in the persistent
store and then size the persistent store accordingly. Because the size of a session
varies from one application to the other, there cannot be a simple formula for sizing the
persistent store. The following example explains the factors that need to be considered
while sizing a session store.
If at maximum capacity the application produces 20,000 sessions per day and if the
session cleanup script is run daily to clean up sessions older than 5 days, the session
store should have capacity to hold a minimum of 5 X 20,000 (=100,000) session
objects. This example assumes that the session expiry duration (session-timeout)
is less than 5 days. For more information on cleaning session table, see the Cleaning
the NonStop SQL Session Data on page 3-94.°@
For any given application, perform the following steps to decide the size of the session
store.
1. Run your application to create 10% of the maximum number of session objects
that are to be stored in the session store. In the above example it is 10% of
100,000 (=10,000).
2. After the sessions are created, locate the physical file of the session table and
determine its size. For more information, Determining the size of the session table
on page 3-92. Ensure that the size of the table is at least 10 times greater than this
size.
The SQL command that can be used to count the number of sessions in the table
is:
select count (distinct session_id) from sessdata;
Determining the size of the session table
To determine the size of the session table, complete the following steps:
1. Obtain the disk file name for the sessions table. For SQL/MX, use the showddl
command. Enter showddl followed by the
<catalog>.<schema>.<tablename> of the session table at the SQL/MX
command interface (mxci) prompt to determine the disk file name. Example 3-73