PMCD(1) General Commands Manual PMCD(1)
pmcd - performance metrics collector daemon
pmcd [-AfQSv] [-c config] [-C dirname] [-H hostname] [-i ipaddress]
[-l logfile] [-L bytes] [-M certname] [-[n|N] pmnsfile] [-p
port[,port ...]] [-P passfile] [-q timeout] [-s sockname] [-T
traceflag] [-t timeout] [-U username] [-x file]
pmcd is the collector used by the Performance Co-Pilot (see
PCPIntro(1)) to gather performance metrics on a system. As a rule,
there must be an instance of pmcd running on a system for any
performance metrics to be available to the PCP.
pmcd accepts connections from client applications running either on
the same machine or remotely and provides them with metrics and other
related information from the machine that pmcd is executing on. pmcd
delegates most of this request servicing to a collection of
Performance Metrics Domain Agents (or just agents), where each agent
is responsible for a particular group of metrics, known as the domain
of the agent. For example the postgresql agent is responsible for
reporting information relating to the PostgreSQL database, such as
the transaction and query counts, indexing and replication
statistics, and so on.
The agents may be processes started by pmcd, independent processes or
Dynamic Shared Objects (DSOs, see dlopen(3)) attached to pmcd's
address space. The configuration section below describes how
connections to agents are specified.
The options to pmcd are as follows.
-A Disable service advertisement. By default, pmcd will
advertise its presence on the network using any available
mechanisms (such as Avahi/DNS-SD), assisting remote monitoring
tools with finding it. These mechanisms are disabled with
this option.
-c config
On startup pmcd uses a configuration file from either the
$PCP_PMCDCONF_PATH, configuration variable in /etc/pcp.conf,
or an environment variable of the same name. However, these
values may be overridden with config using this option. The
format of this configuration file is described below.
-C dirname
Specify the path to the Network Security Services certificate
database, for (optional) secure connections. The default is
/etc/pki/nssdb. Refer also to the -P option. If it does not
already exist, this database can be created using the certutil
utility. This process and other certificate database
maintenance information is provided in the PCPIntro(1) manual
page and the online PCP tutorials.
-f By default pmcd is started as a daemon. The -f option
indicates that it should run in the foreground. This is most
useful when trying to diagnose problems with misbehaving
agents.
-H hostname
This option can be used to set the hostname that pmcd will use
to represent this instance of itself. This is used by client
tools like pmlogger(1) when reporting on the (possibly remote)
host. If this option is not set, the pmcd.hostname metric
will match that returned by pmhostname(1). Refer to the
manual page for that tool for full details on how the hostname
is evaluated.
-i ipaddress
This option is usually only used on hosts with more than one
network interface. If no -i options are specified pmcd
accepts connections made to any of its host's IP (Internet
Protocol) addresses. The -i option is used to specify
explicitly an IP address that connections should be accepted
on. ipaddress should be in the standard dotted form (e.g.
100.23.45.6). The -i option may be used multiple times to
define a list of IP addresses. Connections made to any other
IP addresses the host has will be refused. This can be used
to limit connections to one network interface if the host is a
network gateway. It is also useful if the host takes over the
IP address of another host that has failed. In such a
situation only the standard IP addresses of the host should be
given (not the ones inherited from the failed host). This
allows PCP applications to determine that a host has failed,
rather than connecting to the host that has assumed the
identity of the failed host.
-l logfile
By default a log file named pmcd.log is written in the
directory $PCP_LOG_DIR/pmcd. The -l option causes the log
file to be written to logfile instead of the default. If the
log file cannot be created or is not writable, output is
written to the standard error instead.
-L bytes
PDUs received by pmcd from monitoring clients are restricted
to a maximum size of 65536 bytes by default to defend against
Denial of Service attacks. The -L option may be used to
change the maximum incoming PDU size.
-M certname
By default, pmcd will try to use a certificate called PCP
Collector certificate . The -M option allows this to be
changed.
-n pmnsfile
Normally pmcd loads the default Performance Metrics Name Space
(PMNS) from $PCP_VAR_DIR/pmns/root, however if the -n option
is specified an alternative namespace is loaded from the file
pmnsfile.
-N pmnsfile
Same function as -n, except for the handling of duplicate
Performance Metric Identifiers (PMIDs) in pmnsfile - duplicate
names are allowed with -n they are not allowed with -N.
-P passfile
Specify the path to a file containing the Network Security
Services certificate database password for (optional) secure
connections, and for databases that are password protected.
Refer also to the -C option. When using this option, great
care should be exercised to ensure appropriate ownership
("pcp" user, typically) and permissions on this file (0400, so
as to be unreadable by any user other than the user running
the pmcd process).
-q timeout
The pmcd to agent version exchange protocol (new in PCP 2.0 -
introduced to provide backward compatibility) uses this
timeout to specify how long pmcd should wait before assuming
that no version response is coming from an agent. If this
timeout is reached, the agent is assumed to be an agent which
does not understand the PCP 2.0 protocol. The default timeout
interval is five seconds, but the -q option allows an
alternative timeout interval (which must be greater than zero)
to be specified. The unit of time is seconds.
-Q Require that all remote client connections provide a
certficate.
-S Require that all client connections provide user credentials.
This means that only unix domain sockets, or authenticated
connections are permitted (requires secure sockets support).
If any user or group access control requirements are specified
in the pmcd configuration file, then this mode of operation is
automatically entered, whether the -S flag is specified or
not.
-s sockname
Specify the path to a local unix domain socket (for platforms
supporting this socket family only). The default value is
$PCP_RUN_DIR/pmcd.socket.
-t timeout
To prevent misbehaving clients or agents from hanging the
entire Performance Metrics Collection System (PMCS), pmcd uses
timeouts on PDU exchanges with clients and agents running as
processes. By default the timeout interval is five seconds.
The -t option allows an alternative timeout interval in
seconds to be specified. If timeout is zero, timeouts are
turned off. It is almost impossible to use the debugger
interactively on an agent unless timeouts have been turned off
for its "parent" pmcd.
Once pmcd is running, the timeout may be dynamically modified
by storing an integer value (the timeout in seconds) into the
metric pmcd.control.timeout via pmstore(1).
-T traceflag
To assist with error diagnosis for agents and/or clients of
pmcd that are not behaving correctly, an internal event
tracing mechanism is supported within pmcd. The value of
traceflag is interpreted as a bit field with the following
control functions:
1 enable client connection tracing
2 enable PDU tracing
256 unbuffered event tracing
By default, event tracing is buffered using a circular buffer
that is over-written as new events are recorded. The default
buffer size holds the last 20 events, although this number may
be over-ridden by using pmstore(1) to modify the metric
pmcd.control.tracebufs.
Similarly once pmcd is running, the event tracing control may
be dynamically modified by storing 1 (enable) or 0 (disable)
into the metrics pmcd.control.traceconn, pmcd.control.tracepdu
and pmcd.control.tracenobuf. These metrics map to the bit
fields associated with the traceflag argument for the -T
option.
When operating in buffered mode, the event trace buffer will
be dumped whenever an agent connection is terminated by pmcd,
or when any value is stored into the metric
pmcd.control.dumptrace via pmstore(1).
In unbuffered mode, every event will be reported when it
occurs.
-U username
User account under which to run pmcd. The default is the
unprivileged "pcp" account in current versions of PCP, but in
older versions the superuser account ("root") was used by
default.
-v Verify the pmcd configuration file, reporting on any errors
then exiting with a status indicating verification success or
failure.
-x file
Before the pmcd logfile can be opened, pmcd may encounter a
fatal error which prevents it from starting. By default, the
output describing this error is sent to /dev/tty but it may
redirected to file.
If a PDU exchange with an agent times out, the agent has violated the
requirement that it delivers metrics with little or no delay. This
is deemed a protocol failure and the agent is disconnected from pmcd.
Any subsequent requests for information from the agent will fail with
a status indicating that there is no agent to provide it.
It is possible to specify access control to pmcd based on users,
groups and hosts. This allows one to prevent users, groups of users,
and certain hosts from accessing the metrics provided by pmcd and is
described in more detail in the Section on ACCESS CONTROL below.
On startup pmcd looks for a configuration file named
$PCP_PMCDCONF_PATH. This file specifies which agents cover which
performance metrics domains and how pmcd should make contact with the
agents. An optional section specifying access controls may follow
the agent configuration data.
Warning: pmcd is usually started as part of the boot sequence and
runs initially as root. The configuration file may contain shell
commands to create agents, which will be executed by root. To
prevent security breaches the configuration file should be writable
only by root. The use of absolute path names is also recommended.
The case of the reserved words in the configuration file is
unimportant, but elsewhere, the case is preserved.
Blank lines and comments are permitted (even encouraged) in the
configuration file. A comment begins with a ``#'' character and
finishes at the end of the line. A line may be continued by ensuring
that the last character on the line is a ``\'' (backslash). A
comment on a continued line ends at the end of the continued line.
Spaces may be included in lexical elements by enclosing the entire
element in double quotes. A double quote preceded by a backslash is
always a literal double quote. A ``#'' in double quotes or preceded
by a backslash is treated literally rather than as a comment
delimiter. Lexical elements and separators are described further in
the following sections.
Each line of the agent configuration section of the configuration
file contains details of how to connect pmcd to one of its agents and
specifies which metrics domain the agent deals with. An agent may be
attached as a DSO, or via a socket, or a pair of pipes.
Each line of the agent configuration section of the configuration
file must be either an agent specification, a comment, or a blank
line. Lexical elements are separated by whitespace characters,
however a single agent specification may not be broken across lines
unless a \ (backslash) is used to continue the line.
Each agent specification must start with a textual label (string)
followed by an integer in the range 1 to 510. The label is a tag
used to refer to the agent and the integer specifies the domain for
which the agent supplies data. This domain identifier corresponds to
the domain portion of the PMIDs handled by the agent. Each agent
must have a unique label and domain identifier.
For DSO agents a line of the form:
label domain-no dso entry-point path
should appear. Where,
label is a string identifying the agent
domain-no is an unsigned integer specifying the agent's domain in
the range 1 to 510
entry-point is the name of an initialization function which will be
called when the DSO is loaded
path designates the location of the DSO and this is expected
to be an absolute pathname. pmcd is only able to load
DSO agents that have the same simabi (Subprogram
Interface Model ABI, or calling conventions) as it does
(i.e. only one of the simabi versions will be
applicable). The simabi version of a running pmcd may
be determined by fetching pmcd.simabi. Alternatively,
the file(1) command may be used to determine the simabi
version from the pmcd executable.
For a relative path the environment variable PMCD_PATH
defines a colon (:) separated list of directories to
search when trying to locate the agent DSO. The
default search path is $PCP_SHARE_DIR/lib:/usr/pcp/lib.
For agents providing socket connections, a line of the form
label domain-no socket addr-family address [ command ]
should appear. Where,
label is a string identifying the agent
domain-no is an unsigned integer specifying the agent's domain in
the range 1 to 510
addr-family designates whether the socket is in the AF_INET,
AF_INET6 or AF_UNIX domain, and the corresponding
values for this parameter are inet, ipv6 and unix
respectively.
address specifies the address of the socket within the
previously specified addr-family. For unix sockets,
the address should be the name of an agent's socket on
the local host (a valid address for the UNIX domain).
For inet and ipv6 sockets, the address may be either a
port number or a port name which may be used to connect
to an agent on the local host. There is no syntax for
specifying an agent on a remote host as a pmcd deals
only with agents on the same machine.
command is an optional parameter used to specify a command line
to start the agent when pmcd initializes. If command
is not present, pmcd assumes that the specified agent
has already been created. The command is considered to
start from the first non-white character after the
socket address and finish at the next newline that
isn't preceded by a backslash. After a fork(2) the
command is passed unmodified to execve(2) to
instantiate the agent.
For agents interacting with the pmcd via stdin/stdout, a line of the
form:
label domain-no pipe protocol command
should appear. Where,
label is a string identifying the agent
domain-no is an unsigned integer specifying the agent's domain
protocol The value for this parameter should be binary.
Additionally, the protocol can include the notready
keyword to indicate that the agent must be marked as
not being ready to process requests from pmcd. The
agent will explicitly notify the pmcd when it is ready
to process the requests by sending PM_ERR_PMDAREADY
PDU.
command specifies a command line to start the agent when pmcd
initializes. Note that command is mandatory for pipe-
based agents. The command is considered to start from
the first non-white character after the protocol
parameter and finish at the next newline that isn't
preceded by a backslash. After a fork(2) the command
is passed unmodified to execve(2) to instantiate the
agent.
The access control section of the configuration file is optional, but
if present it must follow the agent configuration data. The case of
reserved words is ignored, but elsewhere case is preserved. Lexical
elements in the access control section are separated by whitespace or
the special delimiter characters: square brackets (``['' and ``]''),
braces (``{'' and ``}''), colon (``:''), semicolon (``;'') and comma
(``,''). The special characters are not treated as special in the
agent configuration section. Lexical elements may be quoted (double
quotes) as necessary.
The access control section of the file must start with a line of the
form:
[access]
Leading and trailing whitespace may appear around and within the
brackets and the case of the access keyword is ignored. No other
text may appear on the line except a trailing comment.
Following this line, the remainder of the configuration file should
contain lines that allow or disallow operations from particular hosts
or groups of hosts.
There are two kinds of operations that occur via pmcd:
fetch allows retrieval of information from pmcd. This may
be information about a metric (e.g. its description,
instance domain or help text) or a value for a metric.
store allows pmcd to be used to store metric values in
agents that permit store operations. This may be the
actual value of the metric (e.g. resetting a counter
to zero). Alternatively, it may be a value used by
the PMDA to introduce a change to some aspect of
monitoring of that metric (e.g. server side event
filtering) - possibly even only for the active client
tool performing the store operation, and not others.
Access to pmcd can be granted in three ways - by user, group of
users, or at a host level. In the latter, all users on a host are
granted the same level of access, unless the user or group access
control mechanism is also in use.
User names and group names will be verified using the local
/etc/passwd and /etc/groups files (or an alternative directory
service), using the getpwent(3) and getgrent(3) routines.
Hosts may be identified by name, IP address, IPv6 address or by the
special host specifications ``"unix:"'' or ``"local:"''. ``"unix:"''
refers to pmcd's unix domain socket, on supported platforms.
``"local:"'' is equivalent to specifying ``"unix:"'' and
``localhost``.
Wildcards may also be specified by ending the host identifier with
the single wildcard character ``*'' as the last-given component of an
address. The wildcard ``".*"'' refers to all inet (IPv4) addresses.
The wildcard ``":*"'' refers to all IPv6 addresses. If an IPv6
wildcard contains a ``::'' component, then the final ``*'' refers to
the final 16 bits of the address only, otherwise it refers to the
remaining unspecified bits of the address.
The wildcard ``*'' refers to all users, groups or host addresses,
including ``"unix:"''. Names of users, groups or hosts may not be
wildcarded.
The following are all valid host identifiers:
boing
localhost
giggle.melbourne.sgi.com
129.127.112.2
129.127.114.*
129.*
.*
fe80::223:14ff:feaf:b62c
fe80::223:14ff:feaf:*
fe80:*
:*
"unix:"
"local:"
*
The following are not valid host identifiers:
*.melbourne
129.127.*.*
129.*.114.9
129.127*
fe80::223:14ff:*:*
fe80::223:14ff:*:b62c
fe80*
The first example is not allowed because only (numeric) IP addresses
may contain a wildcard. The second and fifth examples are not valid
because there is more than one wildcard character. The third and
sixth contain an embedded wildcard, the fourth and seventh have a
wildcard character that is not the last component of the address (the
last components are 127* and fe80* respectively).
The name localhost is given special treatment to make the behavior of
host wildcarding consistent. Rather than being 127.0.0.1 and ::1, it
is mapped to the primary inet and IPv6 addresses associated with the
name of the host on which pmcd is running. Beware of this when
running pmcd on multi-homed hosts.
Access for users, groups or hosts are allowed or disallowed by
specifying statements of the form:
allow users userlist : operations ;
disallow users userlist : operations ;
allow groups grouplist : operations ;
disallow groups grouplist : operations ;
allow hosts hostlist : operations ;
disallow hosts hostlist : operations ;
list userlist, grouplist and hostlist are comma separated
lists of one or more users, groups or host identifiers.
operations is a comma separated list of the operation types
described above, all (which allows/disallows all
operations), or all except operations (which
allows/disallows all operations except those listed).
Either plural or singular forms of users, groups, and hosts keywords
are allowed. If this keyword is omitted, a default of hosts will be
used. This behaviour is for backward-compatibility only, it is
preferable to be explicit.
Where no specific allow or disallow statement applies to an
operation, the default is to allow the operation from all users,
groups and hosts. In the trivial case when there is no access
control section in the configuration file, all operations from all
users, groups, and hosts are permitted.
If a new connection to pmcd is attempted by a user, group or host
that is not permitted to perform any operations, the connection will
be closed immediately after an error response PM_ERR_PERMISSION has
been sent to the client attempting the connection.
Statements with the same level of wildcarding specifying identical
hosts may not contradict each other. For example if a host named
clank had an IP address of 129.127.112.2, specifying the following
two rules would be erroneous:
allow host clank : fetch, store;
disallow host 129.127.112.2 : all except fetch;
because they both refer to the same host, but disagree as to whether
the fetch operation is permitted from that host.
Statements containing more specific host specifications override less
specific ones according to the level of wildcarding. For example a
rule of the form
allow host clank : all;
overrides
disallow host 129.127.112.* : all except fetch;
because the former contains a specific host name (equivalent to a
fully specified IP address), whereas the latter has a wildcard. In
turn, the latter would override
disallow host * : all;
It is possible to limit the number of connections from a user, group
or host to pmcd. This may be done by adding a clause of the form
maximum n connections
to the operations list of an allow statement. Such a clause may not
be used in a disallow statement. Here, n is the maximum number of
connections that will be accepted from the user, group or host
matching the identifier(s) used in the statement.
An access control statement with a list of user, group or host
identifiers is equivalent to a set of access control statements, with
each specifying one of the identifiers in the list and all with the
same access controls (both permissions and connection limits). A
group should be used if you want users to contribute to a shared
connection limit. A wildcard should be used if you want hosts to
contribute to a shared connection limit.
When a new client requests a connection, and pmcd has determined that
the client has permission to connect, it searches the matching list
of access control statements for the most specific match containing a
connection limit. For brevity, this will be called the limiting
statement. If there is no limiting statement, the client is granted
a connection. If there is a limiting statement and the number of
pmcd clients with user ID, group ID, or IP addresses that match the
identifier in the limiting statement is less than the connection
limit in the statement, the connection is allowed. Otherwise the
connection limit has been reached and the client is refused a
connection.
Group access controls and the wildcarding in host identifiers means
that once pmcd actually accepts a connection from a client, the
connection may contribute to the current connection count of more
than one access control statement - the client's host may match more
than one access control statement, and similarly the user ID may be
in more than one group. This may be significant for subsequent
connection requests.
Note that pmcd enters a mode where it runs effectively with a higher-
level of security as soon as a user or group access control section
is added to the configuration. In this mode only authenticated
connections are allowed - either from a SASL authenticated
connection, or a Unix domain socket (which implicitly passes client
credentials). This is the same mode that is entered explicitly using
the -S option. Assuming permission is allowed, one can determine
whether pmcd is running in this mode by querying the value of the
pmcd.feature.creds_required metric.
Note also that because most specific match semantics are used when
checking the connection limit, for the host-based access control
case, priority is given to clients with more specific host
identifiers. It is also possible to exceed connection limits in some
situations. Consider the following:
allow host clank : all, maximum 5 connections;
allow host * : all except store, maximum 2 connections;
This says that only 2 client connections at a time are permitted for
all hosts other than "clank", which is permitted 5. If a client from
host "boing" is the first to connect to pmcd, its connection is
checked against the second statement (that is the most specific match
with a connection limit). As there are no other clients, the
connection is accepted and contributes towards the limit for only the
second statement above. If the next client connects from "clank",
its connection is checked against the limit for the first statement.
There are no other connections from "clank", so the connection is
accepted. Once this connection is accepted, it counts towards both
statements' limits because "clank" matches the host identifier in
both statements. Remember that the decision to accept a new
connection is made using only the most specific matching access
control statement with a connection limit. Now, the connection limit
for the second statement has been reached. Any connections from
hosts other than "clank" will be refused.
If instead, pmcd with no clients saw three successive connections
arrived from "boing", the first two would be accepted and the third
refused. After that, if a connection was requested from "clank" it
would be accepted. It matches the first statement, which is more
specific than the second, so the connection limit in the first is
used to determine that the client has the right to connect. Now
there are 3 connections contributing to the second statement's
connection limit. Even though the connection limit for the second
statement has been exceeded, the earlier connections from "boing" are
maintained. The connection limit is only checked at the time a
client attempts a connection rather than being re-evaluated every
time a new client connects to pmcd.
This gentle scheme is designed to allow reasonable limits to be
imposed on a first come first served basis, with specific exceptions.
As illustrated by the example above, a client's connection is honored
once it has been accepted. However, pmcd reconfiguration (see the
next section) re-evaluates all the connection counts and will cause
client connections to be dropped where connection limits have been
exceeded.
If the configuration file has been changed or if an agent is not
responding because it has terminated or the PMNS has been changed,
pmcd may be reconfigured by sending it a SIGHUP, as in
# pmsignal -a -s HUP pmcd
When pmcd receives a SIGHUP, it checks the configuration file for
changes. If the file has been modified, it is reparsed and the
contents become the new configuration. If there are errors in the
configuration file, the existing configuration is retained and the
contents of the file are ignored. Errors are reported in the pmcd
log file.
It also checks the PMNS file for changes. If the PMNS file has been
modified, then it is reloaded. Use of tail(1) on the log file is
recommended while reconfiguring pmcd.
If the configuration for an agent has changed (any parameter except
the agent's label is different), the agent is restarted. Agents
whose configurations do not change are not restarted. Any existing
agents not present in the new configuration are terminated. Any
deceased agents are that are still listed are restarted.
Sometimes it is necessary to restart an agent that is still running,
but malfunctioning. Simply stop the agent (e.g. using SIGTERM from
pmsignal(1)), then send pmcd a SIGHUP, which will cause the agent to
be restarted.
Normally, pmcd is started automatically at boot time and stopped when
the system is being brought down. Under certain circumstances it is
necessary to start or stop pmcd manually. To do this one must become
superuser and type
# $PCP_RC_DIR/pmcd start
to start pmcd, or
# $PCP_RC_DIR/pmcd stop
to stop pmcd. Starting pmcd when it is already running is the same
as stopping it and then starting it again.
Sometimes it may be necessary to restart pmcd during another phase of
the boot process. Time-consuming parts of the boot process are often
put into the background to allow the system to become available
sooner (e.g. mounting huge databases). If an agent run by pmcd
requires such a task to complete before it can run properly, it is
necessary to restart or reconfigure pmcd after the task completes.
Consider, for example, the case of mounting a database in the
background while booting. If the PMDA which provides the metrics
about the database cannot function until the database is mounted and
available but pmcd is started before the database is ready, the PMDA
will fail (however pmcd will still service requests for metrics from
other domains). If the database is initialized by running a shell
script, adding a line to the end of the script to reconfigure pmcd
(by sending it a SIGHUP) will restart the PMDA (if it exited because
it couldn't connect to the database). If the PMDA didn't exit in
such a situation it would be necessary to restart pmcd because if the
PMDA was still running pmcd would not restart it.
Normally pmcd listens for client connections on TCP/IP port number
44321 (registered at http://www.iana.org/ ). Either the environment
variable PMCD_PORT or the -p command line option may be used to
specify alternative port number(s) when pmcd is started; in each
case, the specification is a comma-separated list of one or more
numerical port numbers. Should both methods be used or multiple -p
options appear on the command line, pmcd will listen on the union of
the set of ports specified via all -p options and the PMCD_PORT
environment variable. If non-default ports are used with pmcd care
should be taken to ensure that PMCD_PORT is also set in the
environment of any client application that will connect to pmcd, or
that the extended host specification syntax is used (see PCPIntro(1)
for details).
$PCP_PMCDCONF_PATH
default configuration file
$PCP_PMCDOPTIONS_PATH
command line options to pmcd when launched from
$PCP_RC_DIR/pmcd All the command line option lines should
start with a hyphen as the first character.
$PCP_SYSCONFIG_DIR/pmcd
additional environment variables that will be set when pmcd
executes. Only settings of the form "PMCD_VARIABLE=value"
will be honoured.
./pmcd.log
(or $PCP_LOG_DIR/pmcd/pmcd.log when started automatically)
$PCP_RUN_DIR/pmcd.pid
contains an ascii decimal representation of the process ID
of pmcd , when it's running.
All messages and diagnostics are directed here
/etc/pki/nssdb
default Network Security Services (NSS) certificate
database directory, used for optional Secure Socket Layer
connections. This database can be created and queried
using the NSS certutil tool, amongst others.
/etc/passwd
user names, user identifiers and primary group identifiers,
used for access control specifications
/etc/groups
group names, group identifiers and group members, used for
access control specifications
In addition to the PCP environment variables described in the PCP
ENVIRONMENT section below, the PMCD_PORT variable is also recognised
as the TCP/IP port for incoming connections (default 44321), and the
PMCD_SOCKET variable is also recognised as the path to be used for
the Unix domain socket.
If set to the value 1, the PMCD_LOCAL environment variable will cause
pmcd to run in a localhost-only mode of operation, where it binds
only to the loopback interface. The pmcd.feature.local metric can be
queried to determine if pmcd is running in this mode.
The PMCD_MAXPENDING variable can be set to indicate the maximum
length to which the queue of pending client connections may grow.
The PMCD_ROOT_AGENT variable controls whether or not pmcd or pmdaroot
(when available), start subsequent pmdas. When set to a non-zero
value, pmcd will opt to have pmdaroot start, and stop, PMDAs.
The PMCD_RESTART_AGENTS variable determines the behaviour of pmcd in
the presence of child PMDAs that have been observed to exit (this is
a typical response in the presence of very large, usually domain-
induced, PDU latencies). When set to a non-zero value, pmcd will
attempt to restart such PMDAS once every minute. When set to zero,
it uses the original behaviour of just logging the failure.
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
configuration file, as described in pcp.conf(5).
If pmcd is already running the message "Error: OpenRequestSocket
bind: Address may already be in use" will appear. This may also
appear if pmcd was shutdown with an outstanding request from a
client. In this case, a request socket has been left in the
TIME_WAIT state and until the system closes it down (after some
timeout period) it will not be possible to run pmcd.
In addition to the standard PCP debugging flags, see pmdbg(1), pmcd
currently uses DBG_TRACE_APPL0 for tracing I/O and termination of
agents, DBG_TRACE_APPL1 for tracing access control and
DBG_TRACE_APPL2 for tracing the configuration file scanner and
parser.
pmcd does not explicitly terminate its children (agents), it only
closes their pipes. If an agent never checks for a closed pipe it
may not terminate.
The configuration file parser will only read lines of less than 1200
characters. This is intended to prevent accidents with binary files.
The timeouts controlled by the -t option apply to IPC between pmcd
and the PMDAs it spawns. This is independent of settings of the
environment variables PMCD_CONNECT_TIMEOUT and PMCD_REQUEST_TIMEOUT
(see PCPIntro(1)) which may be used respectively to control timeouts
for client applications trying to connect to pmcd and trying to
receive information from pmcd.
PCPIntro(1), pmdbg(1), pmerr(1), pmgenmap(1), pminfo(1), pmrep(1),
pmstat(1), pmstore(1), pmval(1), getpwent(3), getgrent(3),
pcp.conf(5), and pcp.env(5).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at ⟨http://www.pcp.io/⟩.
If you have a bug report for this manual page, send it to
pcp@oss.sgi.com. This page was obtained from the project's upstream
Git repository ⟨git://git.pcp.io/pcp⟩ on 2017-07-05. If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
Performance Co-Pilot PCP PMCD(1)
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