The `cfenvgraph' command can use used to dump a graph of averages for
visual inspection of the normal state database. The format of the file
is
t,y_1,y_2,y_3...
which can be viewed using `gnuplot' or
`xgmr' or other graphical plotting program. This would allow the
policy-maker to see what is likely to be a good time for such work (say
06:00 hours), and then use this time for the job, unless an anomalous
load is detected.
The cfenvgraph command is used to extract data from the database used by
the cfenvd environment daemon.
cfenvgraph -f filename.db [-r -T -t -s -e]
The command normally generates two files with format
t, y_1, y_2, y_3, y_4...
in a sub-directory of the current directory `cfenvgraphs-snapshot'
(or `cfenvgraphs-'TIMESTAMP if `-T' is used).
The files are called
cfenv-average
cfenv-stddev
and contain, respectively, the weighted average values of all the
recorded data and the square-root of the weighted variances with respect
to the averages. Data are weighted in such a way that older values are
gradually deprecated, becoming irrelevant after about two months.
Normally the vertical scale of each graph is scaled so that each line
has a maximum value of 1 and a minimum value of 0, this allows all the
lines to be seen in maximum detail. However, this makes it difficult to
see the absolute values of the lines. With the `-n' option, no scaling
is performed and true values are plotted.
The complete data span a one-week
period, and the daily rhythm of the system may normally be viewed as a number
of peaks, one per day.
The options are:
`--help (-h)'
List command options
`--file (-f)'
Specifiy file to plot.
`--titles (-t)'
If the `-t' option is given, comments are generated at the start of the
file which describe the columns. These are in a format understood by
`vvgraph' as title/label data.
`--timestamps (-T)'
If the `-T' option is given,
the output filenames are time-stamped with the current time, in order to
give a unique name.
`--resolution (-r)'
If the `-r' option is given then high resolution data are generated
(five minute resolution), otherwise data are averaged over periods of one hour
to generate simpler and smoother graphs.
`--separate (-s)'
If the `-s' option is given, cfenvgraph generates separate files
for each metric, in the format
t,y,dy
where dy is the height of a vertical error-bar. This set of graphs
combines the average with the standard-deviation. (Note that the
error bars show the standard-deviation, and not the standard error of the
mean i.e. stddev/sqrt(N)); the latter has no obvious meaning here.
If `-e' is specified, then error bars are omitted.
`--no-error-bars (-e)'
No error bars are plotted.
`--no-scaling (-n)'
The graphs are not scaled, so that (min,max) is mapped onto the interval
(0,1).
Note that the values printed for sockets always look higher than
they should for highly active services. This is because even those sockets
which are in CLOSE_WAIT are counted. This is the correct way to determine
a normal state based on the recent past. It is a local averaging performed
by the kernel. If one counts only those connections which are currently
active, one gets a distorted view of activity with a 5-minute sample
rate. To measure more often than this would place unacceptably high load
on the system.
Graphs may be viewed in `vvgraph', `xmgr' (used in the pictures above) or
`gnuplot', or other graphical viewer. These graphs are not meant for
continuous viewing. The data are averages, not time-series.
For example, with gnuplot
host$ cfenvgraph -s
host$ gnuplot
gnuplot> plot "www-in.cfenv" with errorbars
gnuplot> plot "www-in.cfenv" with lines
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