IBM Power7 Optimization And Tuning Manual page 214

• maxfree=(minfree + j2_maxPageReadAhead * number of logical processors).
– The following values are designated as restricted values in AIX V7, and you should not
change them unless directed to do so by AIX support. These values are already in line
with SAS recommendations.
• lru_file_repage (Version 6.1 only).
• minperm% (Version 6.1 only).
• maxperm%.
• maxclient%.
• strict_maxclient.
• strict_maxperm.
– I/O: Tune I/O at the file system layer by using the AIX ioo command to enable
Enhanced Journaled File System (JFS2) to perform efficient caching. Start with the
following parameter values:
• j2_dynamicBufferPreallocation=256.
• j2_nBufferPerPagerDevice=2048.
• j2_maxPageReadAhead=1024.
• j2_minPageReadAhead=16.
• j2_nPagesPerWriteBehindCluster=64.
For higher workloads, increase the value of j2_maxPageReadAhead up to 2048.
– Network: Tune the network parameters by using the no command. If SAS applications
(such as Scalable Performance Data Server (SPDS), Scalable Performance Data
Engine (SPDE), or SAS/CONNECT) are being used, set the following parameter value:
tcp_nodelayack=1
– Maximum user process: If the maximum number of processes for a single user
exceeds 2000, increase the value of maxuproc to prevent SAS processes from
abnormal shutdown or delay. Increase the maxuproc setting by using the AIX smit or
chdev commands, for example:
chdev –l sys0 –a maxuproc=<new value>
– User limits: Increase user-process resource limits for SAS users and database
instances as appropriate (for example, unlimited or some tuned value for all
resources. In the /etc/security/limits file, set -1 for all resources.
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Default AIX resource limits: The default AIX user-process resource limits might be
too low for SAS power users or large enterprise-class deployments of SAS. When
SAS processes end because of attempts to exceed these resource limits, the
system administrator typically sets all of the user process resource limits to
unlimited (a numeric value of -1) for users who run SAS. The problem with this
approach is that the increased multi-threading and scalability support in newer
versions of SAS, coupled with an unlimited setting for user-process resource limits,
allows other users to potentially exhaust system resources, such as processor,
memory I/O, and paging space. Before you increase the user-process resource
limits, such as memory, to high values, consider the potential consequences.