pmmgr - Online in the Cloud

PROGRAM:

NAME

pmmgr - pcp daemon manager

SYNOPSIS

pmmgr [-v] [-c config-directory] [-p polling-interval] [-l log-file]

DESCRIPTION

pmmgr manages a collection of PCP daemons for a set of discovered local and remote hosts
running the Performance Metrics Collection Daemon (PMCD), according to zero or more
configuration directories. It keeps a matching set of pmlogger and/or pmie daemons
running, and their archives/logs merged/rotated. It supplants the older pmlogger_* and
pmie_* check/daily management shell scripts.

pmmgr is largely self-configuring and perseveres despite most run-time errors. pmmgr runs
in the foreground until interrupted. When signaled, it will stop its running daemons
before exiting.

A description of the command line options specific to pmmgr follows:

-c directory adds a given configuration directory to pmmgr. pmmgr can supervise
multiple different configurations at the same time. Errors in the configuration may
be noted to standard error, but pmmgr will fill in missing information with built-in
defaults. The default directory is $PCP_SYSCONF_DIR/pmmgr

-p polling-interval sets the host-discovery polling interval to the given number of
seconds. The default is 60. Daemons for a particular target host will be restarted
no more frequently than this interval.

-l log-file redirects standard output & error to the given log file, which is created
anew

-v adds more verbose tracing to standard output.

CONFIGURATION

A pmmgr configuration identifies which hosts should be monitored, which daemons should be
maintained for them, and what options those daemons should be run with. pmmgr uses a
small number of files in a configuration directory, instead of lines in a text file. The
individual files carry zero or more lines of 100% pure configuration text, and no
comments. (If desired, a configuration may be commented upon with any other file, such as
a free-form README.)

TARGET SELECTION
This set of configuration files identifies where pmmgr should search for pmcd instances,
how to uniquely identify them, and where state such as log files should be kept for each.
Ideally, a persistent & unique host-id string is computed for each potential target pmcd
from specified metric values. This host-id is also used as a subdirectory name for
locating daemon data.

hostid-metrics
This file contains one or more lines of metric specifications in the format
accepted by pmParseMetricSpec. Metrics without instance specifiers mean all
instances of that metric. These are used to generate the unique host-id string for
each pmcd server that pmmgr discovers. Upon discovery, all the metrics/instances
named are queried, string values fetched, and normalized/concatenated into a single
hyphenated printable string. The default is the single metric pmcd.hostname, which
is sufficient if all the hosts discovered have unique hostname(2). If they don't,
you should add other pcp metric specifications to set them apart at your site. The
more you add, the longer the host-id string, but the more likely that accidental
duplication is prevented.

However, it may be desirable for a host-id to also be persistent, so that if the
target host goes offline and later returns, the new host-id matches the previous
one, because then old and new histories can be joined. This argues against using
metrics whose values vary from boot to boot.

Some candidate metrics to consider: network.interface.hw_addr,
network.interface.inet_addr["eth0"], network.interface.ipv6_addr,
kernel.uname.nodename

log-directory
This file contains the path of a directory beneath which the per-host-id
subdirectories are to be created by pmmgr. If it is not a full path, it is
implicitly relative to the configuration directory itself. The default is
$PCP_LOG_DIR/pmmgr/.

target-host
This file contains one or more lines containing pmcd host specifications, as
described on the PCPintro(1) man page. Each poll interval, pmmgr will attempt to
make a brief pmNewContext connection to the host to check liveness. It is not a
problem if more than one specification for the same host is listed, because the
host-id processing eliminates duplicates, and chooses an arbitrary specification
among them. The default is to target pmcd at local:.

target-discovery
This file contains one or more lines containing specifications for the
pmDiscoverServices PMAPI call, each of which may map onto a fluctuating set of
local or remote pmcd servers. Each poll interval, pmmgr will attempt to rerun
discovery with all of the given specifications. Again it is not a problem if more
than one specification matches the same actual pmcd: one confirmed access path is
arbitrarily selected. The default is to do no discovery. Consider including
avahi,timeout=5 to rely in pmcd self-announcements on the local network (searching
for up to five seconds each time).

subtarget-containers
If this file exists, pmmgr will scan each host that is found for running
containers. For each running container, it will create independent subtargets for
running pmlogger instances. The host-id string for these subtargets is the host's
host-id string, followed by a double-hyphen, then the full unique container
instance-name string. (Temporarily, pmie instances are not attempted for these
subtargets, due to PCP bug PR1105.)

log-subdirectory-gc
This file may contain a time interval specification as per the PCPintro man page.
All subdirectories of the log-directory are presumed to contain data for pmmgr-
monitored servers. Those that have not been touched (in the stat/mtime sense) in
at least that long, and not associated with a currently monitored target, are
deleted entirely. This value should be longer than the longest interval that pmmgr
normally recreates archives (such as due to pmmgr restarts, and pmlogmerge
intervals). The default value is 90days.

PMLOGGER CONFIGURATION
This group of configuration options controls a pmlogger daemon for each host. This may
include generating its configuration, and managing its archives.

pmlogger
If and only if this file exists, pmmgr will maintain a pmlogger daemon for each
targeted host. This file contains one line of additional space-separated options
for the pmie daemon. (pmmgr already adds -h, -f, -r, -l, and perhaps -c.) The
default is to maintain no pmlogger (and no other configuration in this section is
processed).

pmlogconf
If and only if this file exists, pmmgr will run pmlogconf to generate a
configuration file for each target pmcd. The file contains one line of space-
separated additional options for the pmlogconf program. pmlogconf's generated
output file will be stored under the log-directory/hostid subdirectory. (pmmgr
already adds -c, -r, and -h.) The default is no pmlogconf, so instead, the
pmlogger file above should probably contain a -c option, to specify a fixed
pmlogger configuration.

ARCHIVE LOG MANAGEMENT
Default pmlogger configurations can collect tens of megabytes of data per day (possibly
split into multiple archives), per target host. If your disk space is less than infinite,
or archive-splitting unwieldy, this should be managed. In the default, unmanaged case,
the system administrator is responsible for managing the individual archive-* files from
the per-host logging subdirectories. pmmgr offers several other options, each
representing different performance / usability tradeoffs.

ARCHIVE LOG MANAGEMENT - pmlogmerge
This style of archive log management regularly creates a single merged archive from prior
archives for each target host, in effect lopping off old data and appending the new. A
single merged archive can be relatively large (defaults to approximately 100-400 MB per
host), and puts a corresponding I/O load on storage, but is most convenient for a detailed
long-timeframe analysis. Once pmlogger is restarted, it always creates a new archive, so
in the steady state, there will be one merged archive of recent history, and one current
archive being written-to by pmlogger.

pmlogmerge
If this file exists, pmmgr will run pmlogextract to periodically merge together
preexisting log archives for each target pmcd into a single large one. Then, the
preexisting log archives are deleted (including any prior merged ones). This
configuration file may contain a time interval specification as per the PCPintro
man page, representing the period after which pmlogger should be temporarily
stopped, and archives merged. It represents the maximum amount of time that the
merged archive lags the present time. The default is 24hours.

pmlogmerge-granular
If this file exists, pmmgr will merge only a subset of preexisting log archives
into the new one, instead of all of them, so as to approximate a granular, aligned
set of merged archives. The subset chosen corresponds to the previous time
interval specified by the pmlogmerge control file. The default is no granularity.

pmlogmerge-rewrite
If this file exists, pmmgr will run pmlogrewrite -i (plus any other options listed
in this file) on each input archive before merging it. This will naturally require
more disk I/O. The default is no rewriting.

pmlogmerge-retain
pmmgr reduces/deletes any original-resolution archives after a time period
specified by this file, as measured by the file mtime. The period will also be
passed to pmlogextract as a negative parameter to -S. The default is 14days. To
store archives indefinitely, set this to a large quantity like "99999weeks".

pmlogreduce
If this file exists, then prior to removing archives that expire past the
pmlogmerge-retain period, they are processed with pmlogreduce to create reduced
archives (named reduced-*). If the file contains space-separated options, they are
passed onto pmlogreduce. (By default, pmlogreduce downsamples to a 600-second
interval.)

pmlogreduce-retain
If this file exists, then reduced archives (identified by the reduced-* pattern)
are deleted after a time period specified by this file, as measured from the file
mtime. Since this time is likely that of the pmlogreduce run, the total retention
time will be approximately the pmlogmerge-retain time plus the pmlogreduce-retain
time. The default is 90days. To store reduced archives indefinitely, set this to
a large quantity like "99999weeks".

PMIE CONFIGURATION
This group of configuration options controls a pmie daemon for each host. This may
include generating a custom configuration.

pmie If and only if this file exists, pmmgr will maintain a pmie daemon for each
targeted pmcd. This file contains one line of additional space-separated options
for the pmie daemon. (pmmgr already adds -h, -f, -l, and perhaps -c.) The default
is to maintain no pmie (and no other configuration in this section is processed).

pmieconf
If and only if this file exists, pmmgr will run pmieconf to generate a
configuration file for each target pmcd. The file contains one line of space-
separated additional options for the pmieconf program. pmieconf's generated output
file will be stored under the log-directory/hostid subdirectory. (pmmgr already
adds -F, -c, and -f.) The default is no pmieconf, so instead, the pmie file above
should probably contain a -c option, to specify a fixed pmie configuration.

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