Editing UBC failcnt reset

One of the frequently asked question is '''How do I reset failcnt in /proc/user_beancounters?''' While it's not suggested, it is possible.

== What is failcnt? ==
There are a number of resource limits (called [[User Beancounters]], or UBC for short) set for a container. If one of those resources hit its limit, the appropriate fail counter (last column of <code>/proc/user_beancounters</code>) increases. See [[Resource shortage]] for more info.

== How to clear failcnt? ==
You do not need to, and this would be an incorrect thing to do.

There can be many applications that read <code>/proc/user_beancounters</code>, and thus if you will reset it, you may have problems with those other apps. Consider what happens if you reset your sent/received packets/bytes statistics on a network interface — programs which track it may not function properly. 

Therefore, the proper usage of failcnt is not to check whether it is zero or not, but to check whether it is increased since the previous readout. In other words, check the difference, not the absolute value. It is easy to write a simple script to do just that.

(See [[#Bash script]] for an example script)

== OK, I understand, but I still want to clear failcnt! ==

UBC failcnts are stored for the duration of the uptime of your container. Thus, restarting the container resets the counts.

The problem here is tcp time wait buckets can still there after a container is stopped. You can check that by seeing the <code>held</code> column for <code>kmemsize</code> parameter. If it is not zero, that means you have to wait about 5 minutes in order to time wait buckets to expire, and the corresponding beancounter to be uncharged.

If you still see failcnt not reset to 0 after more than 5 minutes after container is stopped, your kernel was likely compiled with CONFIG_UBC_KEEP_UNUSED=y, and in that case you'll have to switch off this option if you want to reset beancounters when container is restarted. 

If you're sure your kernel was NOT compiled with the above option and it's not resetting failcnt after 5 minutes, it means there is a bug in UBC code. Please file a detailed [[bug report]] to [http://bugzilla.openvz.org bugzilla.openvz.org]

== Bash script ==

This script can show the failcount deltas for one or all containers since last reset, and reset the failcounts for one or all containers.

It uses only standard commands and programs that are usually included in all linux distro's:
* bash
* cat
* grep
* awk
* head
* tail
* printf

=== Installation ===

[[#beanc source code|Create the script]] and save it somewhere you can use it. This can either be in your home directory, or in a directory mentioned in your path variable (eg. /usr/sbin)

The script is intended to be used as root because it needs write permissions in a directory /var/lib/beanc. If that directory doesn't exist it needs write permissions in /var/lib to be able to create that directory.

You can also run it as any other user that has access to /proc/user_beancounters if you manually fix the permissions on /var/lib/beanc.

=== Show the beancounters ===
 beanc show
this compares the contents of /proc/user_beancounters and the reference file, and shows you the delta value
if no reference file exists, a copy of the user_beancounters file is used.
to only show you the failcounts for 1 container, just add the ctid or container name to the command
 beanc show mailserver
 beanc show 102

=== Reset failcounters ===
 beanc reset mailserver
 beanc reset 102
 beanc reset                   --> will reset failcounters for all containers
Confirmation will be asked.

=== Show only failcounts > 0 ===
 beanc brief

=== Initialize reference file ===
 beanc init

This will check if the app-directory exists (/var/lib/beanc) and create it if necessary
It also creates a reference file (/var/lib/beanc/user_beancounters)

BEWARE, this command will overwrite any existing reference file !

=== beanc source code ===
<source lang=bash>
#!/bin/bash
#####################################################################################################################
#
# This script is intended to check the failcounts in user_beancounters on a OpenVZ machine.
# Since there is no solid way to reset the failcounts, this script maintains a copy of the file and shows delta's
#
#
# Filename: beanc
# Version : 0.1
#
#
# License:
# -------
#
# By using this script you agree there are absolutely no limitations on using it. Ofcourse there are also
# absolutely no guarantees. Please review the code to make sure it will work for you as expected.
#
# Feel free to distribute and/or modify the script.
#
# Only thing I will not appreciate is that you change my name into yours, and act like you wrote this script
# But hey, why would you do that ?  And how will I ever know ?
#
# If you make changes, decide to distribute the script or feel the urge to give me feedback, please let me know.
#
#
# Author(s):
# ---------
#
# Written by Steven Broos, 7/7/2011 in a boring RHEL course
#          Steven@Bit-IT.be
#
#
# Usage:
# -----
#
# 1. Copy the file to a location in your path, for example '/sbin/'
# 2. Make sure the file can be executed ('chmod 500 /sbin/beanc')
# 3. Use the script ;-)  At first execution the reference file will be created in '/var/lib/beanc/'
#     Note that the script is written for intended use by root, and on the OpenVZ host system
#     Possibly this script wont work in a cron-job or inside a container. This has not been tested
#
#
# Options:
# -------
#
# 1. Show the beancounters
#
#          beanc show
#
#     this compares the contents of /proc/user_beancounters and the reference file, and shows you the delta value
#     if no reference file exists, a copy of the user_beancounters file is used.
#     to only show you the failcounts for 1 container, just add the ctid or container name to the command
#
#          beanc show mailserver
#          beanc show 102
#
# 2. To reset the failcounters for a container (or all containers):
#
#          beanc reset mailserver
#          beanc reset 102
#          beanc reset                   --> will reset failcounters for all containers
#
#     Confirmation will be asked.
#
# 3. It is also possible to only show the failcounters > 0
#
#          beanc brief
#
# 4. If for some reason you want to manually initialize the reference file, you can execute
#
#          beanc init
#
#     This will check if the app-directory exists (/var/lib/beanc) and create it if necessary
#     It also creates a reference file (/var/lib/beanc/user_beancounters)
#     BEWARE, this command will overwrite any existing reference file !
#


#####################################################################################################################
####                                                                                                             ####
####  Declaration of some variables. Feel free to adjust                                                         ####
####                                                                                                             ####
#####################################################################################################################


rspath='/var/lib/beanc'
rsfile="$rspath/user_beancounters"
lines=24


#####################################################################################################################
####                                                                                                             ####
####  Function declarations. See at the bottom of the script for execution                                       ####
####                                                                                                             ####
#####################################################################################################################


# show brief help message

function help ()
{
        echo "$0 { reset | show | brief | init } [ <vzid> | <vzname> ]"
        exit 0
}

# check existence of path and reference file, and create if necessary
# This function is executed by every start of the script

function init ()
{
        if [ ! -d "$rspath" ] || [ "$1" != "" ]
        then
                mkdir -p "$rspath"
        fi
        if [ ! -f "$rsfile" ] || [ "$1" != "" ]
        then
                cat /proc/user_beancounters > "$rsfile"
        fi
}

# Reset the failcounters by putting the current values from /proc/user_beancounters into the reference file
# either for all containers (cat > ref), or for one container (block per block)

function reset ()
{
        if [ "$1" == "" ]
        then
                echo -n "Reset failcounts for all containers ? [y/N] "
                read -n 1 yn
                echo
                if [ "$yn" == "y" ]
                then
                        cat /proc/user_beancounters > "$rsfile"
                fi
        else
                echo -n "Reset failcounts for container '`vzname $1`' ($1) ? [y/N] "
                read -n 1 yn
                echo
                if [ "$yn" == "y" ]
                then
                        mv "$rsfile" "${rsfile}_"
                        for ctid in `vzlist -Ho ctid`
                        do
                                if [ $ctid -eq $1 ]
                                then
                                        echo "Resetting '`vzname $ctid`' ($ctid)"
                                        cat /proc/user_beancounters | getblock $ctid >> "$rsfile"
                                else
                                        echo "Keeping '`vzname $ctid`' ($ctid)"
                                        cat "${rsfile}_" | getblock $ctid >> "$rsfile"
                                fi
                        done
                        rm -f "${rsfile}_"
                fi
        fi
}

# Get one or more lines from the middle of the given text : returns the 'head' of a 'tail"
# $1 : start at line
# $2 : give this much lines (optional, default 1)
# example : cat /path/file | getline 10 5

function getline ()
{
        start=$1
        length=$2

        if [ "$length" == "" ]
        then
                length=1
        fi

        cat - | head -n $(($start+$length-1)) | tail -n $length
}

# Get all beancounter values for a container
# $1 : ctid
# example : cat /proc/user_beancounters | getblock 102

function getblock ()
{
        cat - > "$rspath/tmp"
        start=`cat -n "$rspath/tmp" | grep " $1:" | awk '{ print $1 }'`
        echo start $start
        cat "$rspath/tmp" | getline $start $lines
        rm -f "$rspath/tmp"
}

# Show the contents from /proc/user_beancounters, and substitute the failcounts by a delta with the failcounts in
# the reference file
# $1 : ctid (optional, if none given all running containers are processed)
# example : show 102

function show ()
{
        if [ "$1" == "" ]
        then
                for ctid in `vzlist -Ho ctid`
                do
                        show $ctid
                done
        else
                cstart=`cat /proc/user_beancounters -n | grep " $1:" | awk '{ print $1 }'`
                hstart=`cat "$rsfile" -n | grep " $1:" | awk '{ print $1 }'`

                for ln in `seq 0 $(($lines-1))`
                do
                        current=`cat /proc/user_beancounters | getline $(($cstart+$ln))`
                        if [ "$hstart" == "" ]
                        then
                                history=''
                        else
                                history=`cat "$rsfile" | getline $(($hstart+$ln))`
                        fi

                        if [ $ln -eq 0 ]
                        then
                                resource=`echo "$current" | awk '{ print $2 }'`
                                held=`echo "$current" | awk '{ print $3 }'`
                                maxheld=`echo "$current" | awk '{ print $4 }'`
                                barrier=`echo "$current" | awk '{ print $5 }'`
                                limit=`echo "$current" | awk '{ print $6 }'`
                                currfcnt=`echo "$current" | awk '{ print $7 }'`
                                histfcnt=`echo "$history" | awk '{ print $7 }'`

                                fgcolor white
                                echo ' ----------------------------------------------------------------------------------------------------------------------
--'
                                printf "|%14s : %-12s %89s |\n" $1 `vzname $1` "`vzfqdn $1` (`vzip $1`)"
                                printf "|%14s%21s%21s%21s%21s%21s |\n" resource held maxheld barrier limit failcnt
                                echo ' ----------------------------------------------------------------------------------------------------------------------
--'
                                fgcolor reset
                        else
                                resource=`echo "$current" | awk '{ print $1 }'`
                                held=`echo "$current" | awk '{ print $2 }'`
                                maxheld=`echo "$current" | awk '{ print $3 }'`
                                barrier=`echo "$current" | awk '{ print $4 }'`
                                limit=`echo "$current" | awk '{ print $5 }'`
                                currfcnt=`echo "$current" | awk '{ print $6 }'`
                                histfcnt=`echo "$history" | awk '{ print $6 }'`
                        fi
                        if [ "$histfcnt" == "" ]
                        then
                                failcnt=$currfcnt
                        else
                                failcnt=$(($currfcnt-$histfcnt))
                        fi

                        printf ' '
                        if [ $failcnt -gt 0 ]
                        then
                                bgcolor red
                                fgcolor white
                                echo -en '*'
                        else
                                fgcolor green
                                echo -en ' '
                        fi
                        printf "%13s%21s%21s%21s%21s%21s %.s" $resource $held $maxheld $barrier $limit $failcnt "($histfcnt-$currfcnt)"
                        fgcolor reset
                        bgcolor reset
                        echo
                done
        fi
}

# Shows only counters > 0, by grepping on '|' and '-' (for the header), and '*' (for the matching failcounter)
# If no '*' has been found, nothing for that container will be shown

function showbrief ()
{
        echo 'Calculating ...'
        for ctid in `vzlist -Ho ctid`
        do
                result=`show $ctid`
                matches=`echo -en "$result" | grep '*' | wc -l`
                if [ $matches -gt 0 ]
                then
                        echo -en "$result" | grep -e '|' -e '*' -e '-'
                fi
        done
        echo 'Done!'
}

# This function returns the ctid for a container.
# $1 : container-name or even the ctid itself, since you cannot know what value the user has given

function vzid ()
{
        vzlist -o name,ctid | grep -e "^$1 " -e " $1$" | awk '{ print $2 }'
}

# Returns the IP for the given ctid
# $1 : ctid

function vzip ()
{
        vzlist -o ctid,ip | grep " $1 " | awk '{ print $2 }'
}

# Returns the fully qualified domain name for the given ctid
# $1 : ctid

function vzfqdn ()
{
        vzlist -o ctid,hostname | grep " $1 " | awk '{ print $2 }'
}

# Returns the short name for the given ctid
# $1 : ctid

function vzname ()
{
        vzlist -o ctid,name | grep " $1 " | awk '{ print $2 }'
}

# This function outputs the escape code for the specified textcolor
# $1 : Color by name (black, blue, ...)
#      Or reset to revert to the terminal's default colors
# example : fgcolor red; echo 'red text'; fgcolor reset

function fgcolor ()
{
        case $1 in
                'black') echo -en "\033[1;30m" ;;
                'green') echo -en "\033[1;32m" ;;
                'red') echo -en "\033[1;31m" ;;
                'cyan') echo -en "\033[1;36m" ;;
                'white') echo -en "\033[1;37m" ;;
                'reset') tput sgr0 ;;
        esac
}

# This function outputs the escape code for the specified backgroundcolor
# $1 : Color by name (black, blue, ...)
#      Or reset to revert to the terminal's default colors
# example : bgcolor green; echo 'highlighted text'; bgcolor reset

function bgcolor ()
{
        case $1 in
                black) echo -en "\033[0;40m" ;;
                green) echo -en "\033[0;42m" ;;
                red) echo -en "\033[0;41m" ;;
                cyan) echo -en "\033[0;46m" ;;
                white) echo -en "\033[0;47m" ;;
                reset) tput sgr0 ;;
        esac
}


#####################################################################################################################
####                                                                                                             ####
####  Execution                                                                                                  ####
####                                                                                                             ####
#####################################################################################################################


# If no options are given, show a brief help message

if [ "$1" == "" ]
then
        help
fi

# Check initialisation

init

# Get container ID (either by name or ID)

vzid=`vzid $2`

# If a container has been specified ($2) but none was found, give a warning and exit

if [ "$vzid" == "" ] && [ "$2" != "" ]
then
        echo "Container $2 not running"
        exit 1
fi

# Check what to do and call the right functions

case $1 in
        'init')
                init 1
                ;;
        'show')
                # If no container has been specifief, a lot of output can be expected
                # Automatically send it through 'less'. option '-R' makes sure formattion will be kept

                if [ "$2" == "" ]
                then
                        show $vzid #| less -R
                else
                        show $vzid
                fi
                ;;
        'brief')
                showbrief
                ;;
        'reset')
                reset $vzid
                ;;
        *)
                help;
esac
</source>

== Tool ==

See {{Bug|1298}}.

== External links ==
* {{Forum|361}}
* {{Forum|497}}

[[Category:FAQ]]
[[Category:UBC]]