Munin contributed plugins

#!/bin/bash

: << =cut

=head1 NAME

  zfs_arcstats - Munin multi-graph plugin to monitor ZFS ARC statistics

  These functions are implemented:

    size     : to monitor ARC size

    activity : to monitor ARC activities

    actlist  : to monitor ARC activities by cache list (MFU/MRU)

    actdata  : to monitor ARC activities by data type (Demand/Prefetch)

    hitratio : to monitor ARC hit ratio

  Tested with Solaris 10 and 11, OpenIndiana Hipster, FreeBSD 11, CentOS 7

  This plugin is inspired by arcstat.pl [https://github.com/mharsch/arcstat]

=head1 CONFIGURATION

  Make symlink:

    cd /path/to/munin/etc/plugins

    ln -s /path/to/munin/lib/plugins/zfs_arcstats .

  For FreeBSD, it should be necessary to change shebang /bin/bash -> /usr/local/bin/bash

=head1 ENVIRONMENT VARIABLES

  None

=head1 AUTHOR

  K.Cima https://github.com/shakemid

=head1 LICENSE

  GPLv2

=head1 Magic markers

  #%# family=contrib

  #%# capabilities=autoconf

=cut

# Include plugin.sh

. "${MUNIN_LIBDIR:-}/plugins/plugin.sh"

is_multigraph "$@"

# Shell options

set -o nounset

# Set global variables

plugin_name=zfs_arcstats

functions='size activity actlist actdata hitratio'

# Functions

get_osname() {

    local osname osver

    osname=$( uname -s )

    osver=$( uname -v )

    case $osname in

    SunOS)

        case $osver in

        illumos*)

            osname=illumos 

        ;;

        esac

    ;;

    esac

    echo "$osname"

}

preconfig() {

    local func=$1

    # data_attr format: field type draw label

    #   label can contain white-spaces.

    case $func in

    size)

        global_attr="

            graph_title ZFS ARC - Size 

            graph_category fs

            graph_args --base 1024 --lower-limit 0

            graph_vlabel Bytes

            graph_info ZFS ARC - Size

        "

        case $osname in

        SunOS)

            # For Solaris 10,11

            data_attr="

                data_size          GAUGE AREASTACK Data size

                prefetch_meta_size GAUGE AREASTACK Prefetch meta size

                buf_size           GAUGE AREASTACK Buf size

                other_size         GAUGE AREASTACK Other size

            "

            ;;

        *)

            # For illumos, FreeBSD, Linux (OpenZFS)

            data_attr="

                data_size     GAUGE AREASTACK Data size

                metadata_size GAUGE AREASTACK Metadata size

                hdr_size      GAUGE AREASTACK Hdr size

                other_size    GAUGE AREASTACK Other size

                mru_size      GAUGE LINE      MRU size

                mfu_size      GAUGE LINE      MFU size

            "

            ;;

        esac

        data_attr="

            $data_attr

            size GAUGE LINE ARC size

            c    GAUGE LINE Target size

            p    GAUGE LINE Target MRU size

        "

        ;;

    activity)

        global_attr="

            graph_title ZFS ARC - Activities

            graph_category fs

            graph_args --base 1000 --lower-limit 0

            graph_vlabel misses (-) / hits (+) per second

            graph_info ZFS ARC - Activities

            hits.negative misses

            l2_hits.negative l2_misses

        "

        data_attr="

            misses    DERIVE LINE dummy

            hits      DERIVE LINE ARC

            l2_misses DERIVE LINE dummy

            l2_hits   DERIVE LINE L2ARC

        "

        ;;

    actlist)

        global_attr="

            graph_title ZFS ARC - Activities by cache list

            graph_category fs

            graph_args --base 1000 --lower-limit 0

            graph_vlabel ghost hits (-) / hits (+) per second

            graph_info ZFS ARC - Activities by cache list

            mfu_hits.negative mfu_ghost_hits

            mru_hits.negative mru_ghost_hits

        "

        data_attr="

            mfu_ghost_hits DERIVE LINE dummy

            mfu_hits       DERIVE LINE MFU 

            mru_ghost_hits DERIVE LINE dummy

            mru_hits       DERIVE LINE MRU

        "

        ;;

    actdata)

        global_attr="

            graph_title ZFS ARC - Activities by data type

            graph_category fs

            graph_args --base 1000 --lower-limit 0

            graph_vlabel misses (-) / hits (+) per second

            graph_info ZFS ARC - Activities by data type

            demand_data_hits.negative demand_data_misses

            demand_metadata_hits.negative demand_metadata_misses

            prefetch_data_hits.negative prefetch_data_misses

            prefetch_metadata_hits.negative prefetch_metadata_misses

        "

        data_attr="

            demand_data_misses       DERIVE LINE dummy

            demand_data_hits         DERIVE LINE D data

            demand_metadata_misses   DERIVE LINE dummy

            demand_metadata_hits     DERIVE LINE D meta

            prefetch_data_misses     DERIVE LINE dummy

            prefetch_data_hits       DERIVE LINE P data

            prefetch_metadata_misses DERIVE LINE dummy

            prefetch_metadata_hits   DERIVE LINE P meta

        "

        ;;

    hitratio)

        global_attr="

            graph_title ZFS ARC - Hit ratio

            graph_category fs

            graph_args --base 1000 --lower-limit 0 --upper-limit 100 --rigid

            graph_vlabel % hits

            graph_info ZFS ARC - Hit ratio - The graph shows cache hit ratio between munin-update intervals (usually 5 minutes).

            hitratio.cdef                   hits,DUP,misses,+,/,100,*

            l2_hitratio.cdef                l2_hits,DUP,l2_misses,+,/,100,*

            demand_data_hitratio.cdef       demand_data_hits,DUP,demand_data_misses,+,/,100,*

            demand_metadata_hitratio.cdef   demand_metadata_hits,DUP,demand_metadata_misses,+,/,100,*

            prefetch_data_hitratio.cdef     prefetch_data_hits,DUP,prefetch_data_misses,+,/,100,*

            prefetch_metadata_hitratio.cdef prefetch_metadata_hits,DUP,prefetch_metadata_misses,+,/,100,*

        "

        data_attr="

            hits                       DERIVE LINE  dummy

            misses                     DERIVE LINE  dummy

            l2_hits                    DERIVE LINE  dummy

            l2_misses                  DERIVE LINE  dummy

            demand_data_hits           DERIVE LINE  dummy

            demand_data_misses         DERIVE LINE  dummy

            demand_metadata_hits       DERIVE LINE  dummy

            demand_metadata_misses     DERIVE LINE  dummy

            prefetch_data_hits         DERIVE LINE  dummy

            prefetch_data_misses       DERIVE LINE  dummy

            prefetch_metadata_hits     DERIVE LINE  dummy

            prefetch_metadata_misses   DERIVE LINE  dummy

            hitratio                   GAUGE  LINE2 ARC hits

            l2_hitratio                GAUGE  LINE  L2ARC hits

            demand_data_hitratio       GAUGE  LINE  Demand data hits

            demand_metadata_hitratio   GAUGE  LINE  Demand metadata hits

            prefetch_data_hitratio     GAUGE  LINE  Prefetch data hits

            prefetch_metadata_hitratio GAUGE  LINE  Prefetch metadata hits

        "

        ;;

    *)

        echo "Unknown function: $func"

        exit 1

        ;;

    esac 

}

do_config() {

    local func=$1

    local label_max_length=45 

    local field type draw label

    preconfig "$func"

    echo "multigraph ${plugin_name}_${func}"

    # print global attributes

    echo "$global_attr" | sed -e 's/^  *//' -e '/^$/d'

    # print data source attributes

    echo "$data_attr" | while read -r field type draw label

    do

        [ -z "$field" ] && continue

        echo "${field}.type ${type}"

        echo "${field}.draw ${draw}"

        echo "${field}.label ${label:0:${label_max_length}}"

        if [ "$type" = 'DERIVE' ]; then

            echo "${field}.min 0"

        fi

        if [ "$label" = 'dummy' ]; then

            echo "${field}.graph no"

        fi

    done

    echo

}

get_stats() {

    local arcstats stat value

    case $osname in

    SunOS|illumos)

        arcstats=$( kstat -p 'zfs:0:arcstats' | sed -e 's/:/ /g' | awk '{ print $4,$5 }' )

        # kstat output example:

        #   $ kstat -p zfs:0:arcstats

        #   zfs:0:arcstats:c        4135233544

        #   ...

        ;;

    *BSD)

        arcstats=$( /sbin/sysctl -a | sed -n -e 's/^kstat\.zfs\.misc\.arcstats\.//p' | awk -F: '{ print $1,$2 }' )

        # sysctl output example:

        #   $ sysctl -a

        #   ...

        #   kstat.zfs.misc.arcstats.c: 632540160

        #   ...

        ;;

    Linux)

        arcstats=$( sed '1,2d' /proc/spl/kstat/zfs/arcstats | awk '{ print $1,$3 }' )

        # proc file output example:

        #   $ cat /proc/spl/kstat/zfs/arcstats

        #   ...

        #   name        type  data

        #   hits        4     62

        #   ...

        ;;

    *)

        echo "Unsupported OS: $osname"

        exit 1

    esac

    while read -r stat value

    do 

        printf -v "arcstats_${stat}" "%s" "$value" 

        # printf -v means indirect variable assignment (similar to eval)

    done <<< "$arcstats"

}

do_fetch() {

    local func=$1

    local field type draw label value ref

    preconfig "$func"

    echo "multigraph ${plugin_name}_${func}"

    echo "$data_attr" | while read -r field type draw label

    do

        [ -z "$field" ] && continue

        ref="arcstats_${field}" 

        value=${!ref:-0} 

        # ${!varname} means indirect evaluation (similar to eval)

        echo "${field}.value ${value}"

    done

    echo

}

autoconf() {

    if [ -x /sbin/zfs ]; then

        echo yes

    else

        echo "no (ZFS looks unavailable)"

    fi

}

config() {

    local func

    for func in $functions

    do

        do_config "$func"

    done

}

fetch() {

    local func

    get_stats

    for func in $functions

    do

        do_fetch "$func"

    done

}

# Main

osname=$( get_osname )

case ${1:-} in

autoconf)

    autoconf

    ;;

config)

    config

    if [ "${MUNIN_CAP_DIRTYCONFIG:-0}" = "1" ]; then fetch; fi

    ;;

*)

    fetch

    ;;

esac

exit 0