Add or Remove Virtual Processors

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Add or Remove Virtual Processors

Add or Remove Virtual Processors:
 
|-- -p--+-+----+--number--+-AIO-----+-+-------------------------|
        | '- +-'          +-CPU-----+ |
        |                 +-ENCRYPT-+ |
        |                 +-JVP-----+ |
        |                 +-LIO-----+ |
        |                 +-PIO-----+ |
        |                 +-SHM-----+ |
        |                 +-SOC-----+ |
        |                 +-TLI-----+ |
        |                 '-vpclass-' |
        '- ---number--+-CPU-----+-----'
                      +-ENCRYPT-+
                      +-JVP-----+
                      '-vpclass-'

Element	Purpose	Key Considerations
-p number	Adds or removes virtual processors. The number argument indicates the number of virtual processors to add or remove If this value is a negative integer, processors are removed. If this value is a positive integer, processors are added.	Restrictions: You can use the -p option only when the database server is in online mode, and you can add to only one class of virtual processors at a time. For more details, see Adding and Dropping Virtual Processors. Limits: If you are removing virtual processors, the maximum cannot exceed the actual number of processors of the specified type. If you are adding virtual processors, the maximum number depends on the operating system. References: For more information, see the chapter on using virtual processors in the IBM Informix Administrator's Guide.
AIO	Performs nonlogging disk I/O to cooked disk spaces	Also performs nonlogging I/O to raw disk spaces if kernel asynchronous I/O (KAIO) is not used.
CPU	Runs all session threads and some system threads	Limits: It is recommended that the number of CPU VPs not be greater than the number of physical processors. If KAIO is used, performs I/O to raw disk spaces, including I/O to physical and logical logs. Runs thread for KAIO where available or a single poll thread. The database server uses the number of CPU VPs to allocate resources for parallel database queries (PDQ). If you drop CPU VPs, your queries will run significantly slower. The Reinit field of the onstat -g mgm output displays information on the number of queries that are waiting for running queries to complete after an onmode -p command. Also see the IBM Informix Performance Guide.
ENCRYPT	Executes column-level encryption and decryption routines	Specify more ENCRYPT virtual processors if you have multiple encrypted columns.
JVP	Executes Java user-defined routines in the Java Virtual Machine (JVM)	Specify more JVPs if you are running many Java UDRs.
LIO	Writes to the logical-log files if they are in cooked disk space	Use two LIO virtual processors only if the logical logs are in mirrored dbspaces. The database server allows a maximum of two LIO virtual processors.
PIO	Writes to the physical log if it is in cooked disk space	Use two PIO virtual processors only if the physical log is in a mirrored dbspace. The database server allows a maximum of two PIO virtual processors.
SHM	Performs shared-memory communication	You can use the SHM virtual processor even if the database server is not configured for shared-memory communication.
SOC	Uses sockets to perform network communications	You can use the SOC virtual processor only if the database server is configured for network connections through sockets.
STR	Performs stream pipe connections
TLI	Uses the Transport Layer Interface (TLI) to perform network communication	You can use the TLI virtual processor only if the database server is configured for network connections through TLI.
vpclass	Names a user-defined virtual processor class	Additional Information: Use the VPCLASS parameter in the ONCONFIG to define the user-defined virtual-processor class. Specify more user-defined virtual processors if you are running many UDRs. Restrictions: On Windows, you can have only one user-defined virtual processor class at a time. Omit the number parameter in the onmode -p vpclass command. References: For more information on extension classes, see VPCLASS.