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111 lines
4.4 KiB
Plaintext
111 lines
4.4 KiB
Plaintext
<!doctype linuxdoc system>
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<article>
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<title>NSTAT, IFSTAT and RTACCT Utilities
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<author>Alexey Kuznetosv, <tt/kuznet@ms2.inr.ac.ru/
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<date>some_negative_number, 20 Sep 2001
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<abstract>
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<tt/nstat/, <tt/ifstat/ and <tt/rtacct/ are simple tools helping
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to monitor kernel snmp counters and network interface statistics.
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</abstract>
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<p> These utilities are very similar, so that I describe
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them simultaneously, using name <tt/Xstat/ in the places which apply
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to all of them.
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<p>The format of the command is:
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<tscreen><verb>
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Xstat [ OPTIONS ] [ PATTERN [ PATTERN ... ] ]
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</verb></tscreen>
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<p>
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<tt/PATTERN/ is shell style pattern, selecting identifier
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of SNMP variables or interfaces to show. Variable is displayed
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if one of patterns matches its name. If no patterns are given,
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<tt/Xstat/ assumes that user wants to see all the variables.
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<p> <tt/OPTIONS/ is list of single letter options, using common unix
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conventions.
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<itemize>
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<item><tt/-h/ - show help page
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<item><tt/-?/ - the same, of course
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<item><tt/-v/, <tt/-V/ - print version of <tt/Xstat/ and exit
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<item><tt/-z/ - dump zero counters too. By default they are not shown.
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<item><tt/-a/ - dump absolute values of counters. By default <tt/Xstat/
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calculates increments since the previous use.
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<item><tt/-s/ - do not update history, so that the next time you will
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see counters including values accumulated to the moment
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of this measurement too.
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<item><tt/-n/ - do not display anything, only update history.
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<item><tt/-r/ - reset history.
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<item><tt/-d INTERVAL/ - <tt/Xstat/ is run in daemon mode collecting
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statistics. <tt/INTERVAL/ is interval between measurements
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in seconds.
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<item><tt/-t INTERVAL/ - time interval to average rates. Default value
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is 60 seconds.
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<item><tt/-e/ - display extended information about errors (<tt/ifstat/ only).
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</itemize>
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<p>
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History is just dump saved in file <tt>/tmp/.Xstat.uUID</tt>
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or in file given by environment variables <tt/NSTAT_HISTORY/,
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<tt/IFSTAT_HISTORY/ and <tt/RTACCT_HISTORY/.
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Each time when you use <tt/Xstat/ values there are updated.
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If you use patterns, only the values which you _really_ see
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are updated. If you want to skip an unintersting period,
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use option <tt/-n/, or just output to <tt>/dev/null</tt>.
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<p>
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<tt/Xstat/ understands when history is invalidated by system reboot
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or source of information switched between different instances
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of daemonic <tt/Xstat/ and kernel SNMP tables and does not
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use invalid history.
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<p> Beware, <tt/Xstat/ will not produce sane output,
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when many processes use it simultaneously. If several processes
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under single user need this utility they should use environment
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variables to put their history in safe places
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or to use it with options <tt/-a -s/.
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<p>
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Well, that's all. The utility is very simple, but nevertheless
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very handy.
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<p> <bf/Output of XSTAT/
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<p> The first line of output is <tt/#/ followed by identifier
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of source of information, it may be word <tt/kernel/, when <tt/Xstat/
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gets information from kernel or some dotted decimal number followed
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by parameters, when it obtains information from running <tt/Xstat/ daemon.
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<p>In the case of <tt/nstat/ the rest of output consists of three columns:
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SNMP MIB identifier,
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its value (or increment since previous measurement) and average
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rate of increase of the counter per second. <tt/ifstat/ outputs
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interface name followed by pairs of counter and rate of its change.
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<p> <bf/Daemonic Xstat/
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<p> <tt/Xstat/ may be started as daemon by any user. This makes sense
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to avoid wrapped counters and to obtain reasonable long counters
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for large time. Also <tt/Xstat/ daemon calculates average rates.
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For the first goal sampling interval (option <tt/-d/) may be large enough,
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f.e. for gigabit rates byte counters overflow not more frequently than
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each 40 seconds and you may select interval of 20 seconds.
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From the other hand, when <tt/Xstat/ is used for estimating rates
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interval should be less than averaging period (option <tt/-t/), otherwise
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estimation loses in quality.
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Client <tt/Xstat/, before trying to get information from the kernel,
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contacts daemon started by this user, then it tries system wide
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daemon, which is supposed to be started by superuser. And only if
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none of them replied it gets information from kernel.
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<p> <bf/Environment/
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<p> <tt/NSTAT_HISTORY/ - name of history file for <tt/nstat/.
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<p> <tt/IFSTAT_HISTORY/ - name of history file for <tt/ifstat/.
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<p> <tt/RTACCT_HISTORY/ - name of history file for <tt/rtacct/.
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</article>
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