For the latest version of Glance (and MeasureWare/OVPA) logical I/Os are not being measured. In Glance, the logl Rds and loglWts are marked: “na“. For MWA (MeasureWare or OVPA) there are no readings stored for logical (that is, memory resident) reads and writes. The midaemon process retrieves raw information from the kernel as event traces and these are gathered as quickly as possible by the ‘reader’ portion of the code. In order to buffer massive bursts of data, this raw information is stored in a shared memory area so the ‘writer’ portion of the code can independently write the data to the measurement interface. For large scale systems (16 or more processors, 4 Gbit or higher storage connections), the logical read/write rate can easily reach into the 100’s of thousands per second and thus overrun the midaemon memory area (too many reads, not enough writes). The error seen in the /var/opt/perf/status.scope file is:
GBL_LOST_MI_TRACE_BUFFERS
To fix this in C.04 versions, memory areas for midaemon must be adjusted.
CPUs midaemon parameters
8-15 -bufsets 16 -skipbuf 8 -smdvss 256M
16-31 -bufsets 24 -skipbuf 12 -smdvss 256M
32-63 -bufsets 32 -skipbuf 16 -smdvss 512M
64+ -bufsets 32 -skipbuf 16 -smdvss 512M
Make sure your kernel parameter maxdsiz is at least 2048 MB or larger to accommodate the larger midaemon process. Additionally, the option -no_fileio_traces may have to be set for midaemon. This is done in the file /etc/rc.config.d/ovpa by adding (or modifying) the MIPARMS variable:
export MIPARMS = “-p -no_fileio_traces -bufsets 32 -skipbuf 16 -smdvss 512M”
The -p option makes midaemon permanent so the command line settings will not be lost when other performance tools are restarted. The -no_fileio_traces option will disable logical I/O metrics. Note that some installations may not have an ovpa startup script but have an mwa script.
To enable the new settings, use the commands:
ovpa stop
midaemon -T
ovpa start
For some installations, ovpa may not exist in which case you would edit the mwa file rather than the ovpa file. The setting would be:
MWA_START=1
# see the script /opt/perf/bin/mwa for special handling of midaemon parms
MWA_START_COMMAND=”/opt/perf/bin/mwa start -midaemon -fileio_traces -p”
Verify that midaemon is running with the options: -fileio_traces -p and if not, manually run midaemon with the options. Starting with version C.05, the option -no_fileio_traces is the default value, resulting in “na” for Glance and no logical I/O metrics for MWA. However, midaemon was enhanced for C.05 and can handle a larger number of event traces so turning the option back on is a viable option. Just check the /var/opt/perf/status.scope
logfile for errors. The command line parameters for the ovpa startup config file would be:
export MIPARMS=”-p -no_fileio_traces”
– See more at: http://serviceitdirect.com/blog/glance-reports-na-logical-ios#sthash.u5Vpm3uS.dpuf
Tags: HP-UX