pmwtf - compares archives and report significant differences
pmwtf [-dz] [-p precision] [-q thres] [-S starttime] [-T endtime] [-B starttime] [-E end-
time] [-x metric] [-X file] [-Z timezone] archive1 [archive2]
pmwtf compares the average values for every metric in either one or two archives, in a
given time window, for changes that are likely to be of interest when searching for per-
The archive log has the base name archive and must have been previously created using
pmlogger(1). The pmlogsummary(1) utility is used to obtain the average values used for
There are two sorts of invocation of the tool: with either one or two archives.
In the first case, the only sensible command line requires use of all four time window
arguments. These are specified using the same time window format described in PCPIn-
tro(1), and are -S and -T for the start and end times of the first time window of interest
in the archive, and -B and -E for the start and end times of the second time window of
In the second case, with two archives, the -B and -E options might be unnecessary. This
might be the case, for example, when comparing the same time window of two consecutive
days (usually two separate archives), or a time window on the same day of different weeks.
In either case, pmwtf produces a sorted summary of those metrics in the specified window
whose values have deviated the most from a minimal threshold. The level of deviation is
calculated by dividing the average value of each metric in both logs, and then calculating
whether the ratio falls outside of a range considered normal. This ratio can be adjusted
using the -q option, and by default it is 2 (i.e. report all metrics with average values
that have more than doubled in the two time windows or more than halved in the two time
Should any metrics be present in one window but missing from the other, a diagnostic will
be displayed listing each missing metric and the archive from which it was missing.
The remaining options control the specific information to be reported. Metrics with
counter semantics are converted to rates before being evaluated.
-p Print all floating point numbers with precision digits after the decimal place.
-x Compare each metric in each archive in the time windows specified to a given egrep(1)
pattern, excluding those that match from the report output.
-X Allows a file to be specified which containing egrep(1) patterns which are applied to
the metric names to optionally exclude some from the report.
-z Use the local timezone from the given archives.
-Z Changes the timezone in the archive labels to timezone in the format of the environ-
ment variable TZ as described in environ(5).
Default directory for PCP archives containing performance metric values col-
lected from the host hostname.
Environment variables with the prefix PCP_ are used to parameterize the file and directory
names used by PCP. On each installation, the file /etc/pcp.conf contains the local values
for these variables. The $PCP_CONF variable may be used to specify an alternative config-
uration file, as described in pcp.conf(5).
PCPIntro(1), pmlogger(1), pmlogsummary(1), egrep(1), pcp.conf(5) and pcp.env(5).
Performance Co-Pilot PCP PMWTF(1)