Database extents sizing

Tivoli® Netcool® Performance Manager systems are deployed with a database, which contains five default tablespaces for holding traffic data. These tablespaces are as follows:

  • TRAFFIC_SMALL
  • TRAFFIC_MEDIUM
  • TRAFFIC_LARGE
  • TRAFFIC_JUMBO
  • TRAFFIC_JUMBOPLUS

The default traffic tablespaces are configured with different extent sizes so that data can be stored in the correct tablespace for the associated data growth rate. The aim is to ensure that data is stored in the database for efficient data access and data storage. Tables must be stored in tablespaces with appropriate extent sizes.

The default extent sizes that are included with a Tivoli Netcool Performance Manager system are listed in the following section. You must update the default extent sizes to the values obtained from the customer-specific sizing tool. One approach is to size the extents so that a maximum of 10 extents are created per day. The extent size will be 1/10 of the table growth rate per day:
TRAFFIC_JUMBOPLUS       		1024 KBs      		(1 MB)
TRAFFIC_JUMBO      				512 KBs      			(0.5 MB)
TRAFFIC_LARGE      				256 KBs      			(0.25 MB)
TRAFFIC_MEDIUM     				256 KBs      			(0.25 MB)
TRAFFIC_SMALL      				128 KBs      			(0.125 MB)

For example, with the default extent sizes mentioned earlier, if a table is stored in TRAFFIC_JUMBOPLUS, each table, table partition, or both are allocated 1 MB. When a new partition is created, it is created with an initial size of 1 MB. Also, when data is loaded into the table and the table grows, it grows in chunks of 1 MB extents.

It is important to correctly size the extent sizes before you deploy a Tivoli Netcool Performance Manager system. Oversizing a tablespace extent results in wasted disk space. Undersizing a tablespace extent results in the system continually having to create extents and so can be inefficient. One method for estimating the extent size is to use the Technology Pack Dimensioning tool.

The Technology Pack Dimensioning tool can be used to calculate the estimated daily tablespace size per table. This list of tables can then be split into five groups of tables and used to determine the boundaries for each tablespace and the optimal extent size.

After the five extent sizes are calculated, they can be used to update the uniAllocSize parameter that is associated with the TablespaceAttributes section, for each tablespace in a customer's vtdb.dbt database template. The following is an example of the TablespaceAttributes for the TRAFFIC_SMALL tablespace. Note the <uniAllocSize unit="KB"> line. You must update this value to the correct extent size:

      <TablespaceAttributes id="TRAFFIC_SMALL">
         <online>true</online>
         <offlineMode>1</offlineMode>
         <readOnly>false</readOnly>
         <temporary>false</temporary>
         <defaultTemp>false</defaultTemp>
         <undo>false</undo>
         <local>true</local>
         <blockSize>-1</blockSize>
         <allocation>2</allocation>
				<uniAllocSize unit="KB">128</uniAllocSize>
				<initSize unit="KB">-1</initSize>
         <increment unit="KB">-1</increment>
         <incrementPercent>-1</incrementPercent>
         <minExtends>-1</minExtends>
         <maxExtends>-2</maxExtends>
         <minExtendsSize unit="KB">-1</minExtendsSize>
         <logging>true</logging>
         <recoverable>false</recoverable>
         <maxFreeSpace>0</maxFreeSpace>
         <autoSegmentMgmt>false</autoSegmentMgmt>
         <bigfile>false</bigfile>
         <datafilesList>
            <TablespaceDatafileAttributes id="/oradata02/{DB_UNIQUE_NAME}/traffic_small01.dbf">
               <id>-1</id>
            </TablespaceDatafileAttributes>
         </datafilesList>
      </TablespaceAttributes>

Additionally, for each Technology Pack that is to be loaded on a Tivoli Netcool Performance Manager system, each table must be assigned to an appropriate tablespace. A table must be assigned to a tablespace, where no more than 10 extents are created per day.

A method for determining default extent sizes and for deciding which tablespace must be used for a table is described in the Dimensioning procedure.

When new extent sizes are determined, they might be changed on the system by editing the customer database template vtdb.dbt file. You must edit the template at the time of installation before the database is created. See Updating customer database template.