CPU Usage Examples
You have several options for controlling compression on nodes that give you flexibility in determining whether to spend CPU cycles on compression on a global or node-by-node basis.
Stop Using Compression
To completely stop using compression, specify the following in the initialization parameters file:
COMPRESS.EXT=DISALLOW
COMPRESS.STD=DISALLOW COMPRESS.NETMAP.OVERRIDE=DISALLOW |
These values will prevent compression from being performed, and will not allow any netmap entries to override the compression controls with regards to Processes under this node's control.
If the partner node(s) have CCF, then they will respond to these negotiation specifications by either terminating compression, or by sending an SCPA994I, RC=8 message to show that their system specified FORCE as one of the compression types.
If the partner node does not have CCF, compression will be stopped only when this node is the PNODE (with the exception of PRECOMP files, which are precompressed files). If this system is the SNODE, then a message will be written to the RPLERRCK trace file when it is forced to do compression because the PNODE does not have CCF.
Prevent Standard Compression
To prevent only standard compression, specify the following:
| COMPRESS.STD=DISALLOW COMPRESS.NETMAP.OVERRIDE=DISALLOW |
In this case, only Processes specifying COMPRESS will be affected on this node. If the partner node has CCF, then all Process steps that specify COMPRESS will be forced to no compression. However, if the partner has specified COMPRESS=FORCE, then the step will fail with an SCPA994I, RC=8 message.
When a partner node is the PNODE and does not have CCF, then the compression specified in their Process will be performed. If the compression that is being done is disallowed on this node, then the node will write a message to the RPLERRCK trace file to note the situation.
Control Compression on a Node-by-Node Basis
To control compression on a node-by-node basis, you can specify the following initialization parameter (or simply allow the parameter to default):
| COMPRESS.NETMAP.OVERRIDE=ALLOW |
You can then set the netmap compression parameters for each node as needed to allow extended and/or standard compression.
You can also set up the reverse situation on a node-by-node basis, where only certain nodes are prevented from using compression. In this case, specify COMPRESS.NETMAP.OVERRIDE=ALLOW in the initialization parameters file and specify the following netmap parameters for the nodes that will not use compression:
COMPRESS.EXT=DISALLOW
COMPRESS.STD=DISALLOW |