pmsnap - generate performance summary snapshot images
$PCP_BINADM_DIR/pmsnap [-NV] [-C dir]
[-c configs] [-n names] [-o dir]
[-t type]
pmsnap is a shell script that is normally run periodically
from crontab(1) to generate graphic images of pmchart(1)
performance charts. These images can be in any of the supported
pmchart formats, including png, bmp, and jpeg,
and may be incorporated into the content offered by the local Web server.
The -V option enables verbose tracing of the actions. By default
pmsnap generates no output unless some error or warning condition is
encountered.
pmsnap generates images according to its control file,
$PCP_PMSNAPCONTROL_PATH (or dir/control if the -C
option is specified), and uses archive logs created by pmlogger(1) or
PCP archive folios created by pmafm(1) and pmlogger_check(1).
Before attempting to configure pmsnap, it is strongly recommended
that pmlogger be configured according to the descriptions in
pmlogger_daily(1), pmlogger_check(1) and
pmlogger(1).
Once pmlogger has been configured, it is necessary to
configure pmsnap as follows;
- 1.
- Edit the control file $PCP_PMSNAPCONTROL_PATH. The syntax of this
file is described in the comment at the head of the file and an example is
supplied for one and twelve hour "Summary" performance charts
for the local host. Suitable arguments for pmchart are also
described in the comment. The user should consult pmchart for
further details. Note that when pmsnap is run, it globally
substitutes the string LOCALHOSTNAME with the name of the local
host in the control file.
- 2.
- Test the configuration by running
$PCP_BINADM_DIR/pmsnap. Without any arguments pmsnap will
process every non-comment line in $PCP_PMSNAPCONTROL_PATH. The
output images will be placed in the files named in the first field of each
line in the control file, with the file format appended if necessary. If
these file names do not start with / or . then they are
assumed relative to dir, as specified with the -o option.
The default dir is the current directory. Note that if
pmlogger has only been recently started (within about the last 15
minutes), snap-shot images may not be produced and no error messages will
be issued - the reason is that pmchart can not use very short
archives and hence, neither can pmsnap. For debugging purposes the
-V flag should be used.
- 3.
- Add an appropriate entry for pmsnap in the root user's
crontab. An example is supplied in
$PCP_VAR_DIR/config/pmlogger/crontab.
- 4.
- Incorporate the pmsnap images into the local WWW content. Usually,
WWW pages use images that are relative to a particular document root, so
it is often convenient to use the -o command line option to specify
a sub-directory of the local WWW content, and then create a web page in
this directory that shows the snapshot images with text and other content
appropriate to the local environment.
pmsnap accepts the following command line options;
- -C dir
- The control file is located in the directory dir rather than
in the default $PCP_PMSNAPCONTROL_PATH location.
- -c
config-pattern
- Only process lines in the control file which match the
config-pattern regular expression in the Config column.
- -n
name-pattern
- Only process lines in the control file which match the name-pattern
regular expression (see egrep(1)) in the Name column.
- -o dir
- The output images having file names which do not start with / or
. will be placed in a directory relative to dir, otherwise
the output directory is relative to the current directory (i.e. the
default value for dir is ./). Note that dir must be a
writable directory path and may be on an NFS or CIFS file system.
The -N option enables a ``show me'' mode, where the actions
are echoed, but not executed, in the style of ``make -n''. Using -N
in conjunction with -V maximizes the diagnostic capabilities for
debugging.
When either -n or -c are used, pmsnap will
only process lines in the control file which match all the supplied
patterns. If no patterns are given, then all lines will be processed. These
arguments allow multiple entries for pmsnap in crontab so that
different performance summary images can be generated at different times or
with different frequencies.
A sample HTML page, suitable for the Summary snapshot may be found
in $PCP_VAR_DIR/config/pmsnap/Summary.html.
Although pmsnap attempts to flush stdio(3) output
buffers in the relevant pmlogger processes before generating
snap-shots images, this may fail for assorted reasons and no error message
will be given.
pmsnap should not be invoked immediately after
pmlogger_daily has rolled the logs because the new archive logs will
be too short to obtain meaningful results. Note however that pmsnap
will not report errors from pmchart about not being able to comply
with the -A option on very short archives. In these cases no error
will be reported and no output images will be produced.
- $PCP_PMSNAPCONTROL_PATH
- pmsnap control file
- $PCP_VAR_DIR/config/pmsnap/Summary
- summary view for pmchart
- $PCP_VAR_DIR/config/pmsnap/Summary.html
- sample HTML page for summary snapshot
- $PCP_LOG_DIR/pmlogger/hostname/Latest
- PCP archive folio for the host hostname, as generated by
pmlogger_check
- $PCP_VAR_DIR/config/pmlogger/crontab
- example crontab entry