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Manual Reference Pages  -  DTOP (1)


dtop - display and update information about processes on a cluster of machines


Interactive Mode
See Also


dtop [-bqtv] [-f fanout] [-g rungroup1,...,rungroupN] [-l username] [-o porttimeout] [-p portnum] [-w node1,...,nodeN] [-x node1,...,nodeN] [-m proc | load] [-i interval] [command ...]


The dtop command can be used to remotely monitor a cluster of machines for CPU and process information. It provides the same information as the top program, but rather than showing it just for one machine, it gathers the information from a cluster of machines, and sorts it all together into a single, periodically updating report. The following options are available:
-b The -b flag causes dtop to run one iteration on each node, and print out a single report of the processes running on those nodes, rather than continuously updating.
-m The -m option determines if the output is process output, or load average output. Load average output gives the load average, and memory usage statistics for the machines being monitored. Process output gives a list of processes on each machine, sorted by cpu usage. The default mode is proc.
-i The -i flag selects the interval of time between the update of each nodes process or load information. It is not wise to set this value too low, otherwise you may produce uneccesary load on the target hosts. The interval is specified in seconds.
-f If the -f option is specified, followed by a number, it sets the fanout size of the cluster. The fanout size is the number of nodes a command will run on in parallel at one time. Thus a 80 node cluster, with a fanout size of 64, would run 64 nodes in parallel, then, when all have finished, it would execute the command on the last 16 nodes. The fanout size defaults to 64. This option overrides the FANOUT environment variable.
-g If the -g option is specified, followed by a comma separated list of group names, the command will only be run on that group of nodes. A node may be a part of more than one group if desired, however running without the -g option will run the command on the same node as many times as it appears in the file specified by the CLUSTER environment variable. This option is silently ignored if used with the -w option.
-l If the -l option is specified, followed by a username, the commands will be run under that userid on the remote machines. Consideration must be taken for proper authentication, for this to work.
-o The -o option is used to set the timeout in seconds to be used when testing remote connections. The default is five seconds.
-p The -p option can be used to set the port number that testing should occur on when testing remote connections. The default behavior is to guess based on the remote command name.
-q The -q option does not issue any commands, but displays information about the cluster, and the fanout groupings.
-t The -t option causes dtop to attempt a connection test to each node prior to attempting to run the remote command. If the test fails for any reason, the remote command will not be attempted. This can be useful when clusterfiles have suffered bitrot and some nodes no longer exist, or might be down for maintenance. The default timeout is 5 seconds. The timeout can be changed with the -o option. dtop will attempt to guess the port number of the remote service based on your RCMD_CMD setting. It knows about ssh and rsh. If dtop fails to guess your port correctly, you may use the -p argument to set the remote port number. If the RCMD_TEST environment variable exists, the testing will automatically take place.
-v Prints the version of ClusterIt to the stdout, and exits.
-w If the -w option is specified, followed by a comma delimited list of machine names, the command will be run on each node in the list. Without this option, dtop runs on the nodes listed in the file pointed to by the CLUSTER environment variable.
-x The -x option can be used to exclude specific nodes from the cluster. The format is the same as the -w option, a comma delimited list of machine names. This option is silently ignored if used with the -w option.


dtop utilizes the following environment variables.
CLUSTER Contains a filename, which is a newline separated list of nodes in the cluster.
RCMD_CMD Command to use to connect to remote machines. The command chosen must be able to connect with no password to the remote host. Defaults to rsh
RCMD_CMD_ARGS Arguments to pass to the remote shell command. Defaults to none.
RCMD_PORT The port number used to test remote connections. See the -p flag.
RCMD_TEST When set, dtop will automatically test all hosts before launching the remote command. See the -t option for more information.
  The timeout in seconds to use when testing for remote connections.
RCMD_USER The username to connect to remote machines as by default.
FANOUT When set, limits the maximum number of concurrent commands sent at once. This can be used to keep from overloading a small host when sending out commands in parallel. Defaults to 64. This environment setting can be overridden by the -f option.


When dtop is running in interactive mode, it reads commands from the terminal and acts upon them accordingly. During interactive mode, every few seconds, depending on the interval, dtop will query the next few hosts in the cluster, and merge the data from those hosts into the display. The number of hosts updated each interval, is determined by the fanout setting.

Certain characters cause immediate action by dtop. These are
p Switch the mode to the process mode, sorted by the CPU usage of each process.
m Switch the mode to the process mode, sorted by the memory usage of each process.
l Switch the mode to the load average mode, sorted by hostname.
v Switch the mode to the load average mode, sorted by load average.
a Switch the mode to the load average mode, sorted by active memory.
i Switch the mode to the load average mode, sorted by inactive memory.
r Switch the mode to the load average mode, sorted by file cache/buffer memory.
f Switch the mode to the load average mode, sorted by free memory.
s Switch the mode to the load average mode, sorted by swap used.
? Display the interactive help menu.
q Quit dtop


The file pointed to by the CLUSTER environment variable has the following format:

This example would have pollux and castor a member of no groups, rigel and kent a member of group ’alpha’, and alshain and altair a member of group 'sparc'. Note the format of the GROUP command, it is in all capital letters, followed by a colon, and the group name. There can be no spaces following the GROUP command, or in the name of the group.

There is also a LUMP command, which is identical in syntax to the GROUP command. This command allows you to create a named group of groups. Each member of the lump is the name of a group. The LUMP command is terminated by another LUMP or GROUP command, or the EOF marker.

Any line beginning with a '#' symbol denotes a comment field, and the entire line will be ignored. Note that a hash mark placed anywhere other than the first character of a line, will be considered part of a valid hostname or command.


dsh(1), ssh(1), top(1)


The dtop command appeared in clusterit 2.5. Work on dtop was made possible by a generous donation from Mach1 Computing, LLC.


dtop was written by Tim Rightnour.


Solaris 2.5.1 has a maximum of 256 open file descriptors. This means that dtop will fail on a fanout size greater than about 32-40 nodes.

dtop uses the top command in batch mode to collect data from remote machines. Because of this, the top command must exist on the remote node, and additionally, dtop must understand it’s output. dtop should be able to understand output from top on NetBSD, Solaris, and Linux, however, it is possible that if the format were to change, or be different, it would break. If dtop fails to work for you, please send the output of:

top -Sb 20

top -bn 1

to, or file a bug report on sourceforge.

dtop is still rather new, and is likely to still have a few display bugs and parsing issues.

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