How to test the memory on a running linux server?30.05.15

save the below script to memtest.sh
create bz file to linux.tar.bz2
and test the script with :
memtest.sh -x -c 1 -n 2

#!/bin/bash
    #
    # memtest
    #
    # A general purpose memory tester script, with options for enabling extra
    # simultaneous tests in an attempt to test the capacity of the power supply
    # in the machine.  You can find the original source of this script and
    # additional documentation on its usage by visiting my work web page at
    # http://people.redhat.com/~dledford/
    #
    # Author: Doug Ledford  + contributors
    #
    # (C) Copyright 2000-2002,2008,2012 Doug Ledford; Red Hat, Inc.
    # This shell script is released under the terms of the GNU General
    # Public License Version 3, June 2007.  If you do not have a copy
    # of the GNU General Public License Version 3, then one may be
    # retrieved from http://people.redhat.com/~dledford/gpl.txt
    #

# Here we set the defaults for this script.  You can edit these to
    # make permanent changes, or you can pass in command line arguments to
    # make temporary changes
    TEST_DIR=/tmp
    SOURCE_FILE=linux.tar.bz2
    NR_PASSES=20
    HELP=
    PARALLEL=no
    EXTRACT=yes
    MB=1048576

usage ()
    {
    	echo "Usage: `basename $0` [options]"
    	echo "Options:"
    	echo "	-u	Display this usage info"
    	echo "	-h	Give full help description of each option"
    	echo "	-t "
    	if [ -n "$HELP" ]; then
    	echo "		The directory where we will unpack the tarballs and run"
    	echo "		the diff comparisons.  Ideally, this will hit all local"
    	echo "		disks by being part of a software raid array (if there"
    	echo "		is more than one local disk anyway).  It can also be on"
    	echo "		a network file server if you have both a very fast disk"
    	echo "		array on the server, and a very fast network inter-"
    	echo "		connect between the server and your machine (10GBit/s"
    	echo "		or faster is needed in order to out run a single modern"
    	echo "		SATA hard drive that's local)."
    	fi
    	echo "		Default: /tmp"
    	echo "	-s "
    	if [ -n "$HELP" ]; then
    	echo "		The file we will decompress and untar to create the"
    	echo "		file trees we intend to compare against each other.  I"
    	echo "		recommend that this file be a tar.bz2 file and that you"
    	echo "		have the parallel bzip2 utility (pbzip2) installed on"
    	echo "		your machine.  This at least allows the bzip2 unzip"
    	echo "		operation to use all CPUs when not running the test in"
    	echo "		parallel mode.  This file is expected to be in the test"
    	echo "		directory.  You can use a relative path from the test"
    	echo "		directory in case it is located somewhere else."
    	fi
    	echo "		Default: linux.tar.bz2"
    	echo "	-x	Toggle whether or not we extract the contents of the"
    	echo "		tarball, or just decompress it."
    	if [ -n "$HELP" ]; then
    	echo "		In the event that extracting lots of small files slows"
    	echo "		your disk subsystem down too much and our overall write"
    	echo "		speed falls too low, it won't make an effective test of"
    	echo "		the disk DMA operations against CPU memory operations."
    	echo "		If your write speeds aren't high enough, try disabling"
    	echo "		extraction and see if that speeds things up."
    	fi
    	echo "		Default: extract the contents"
    	echo "	-n "
    	if [ -n "$HELP" ]; then
    	echo "		How many times we will run the test before we consider"
    	echo "		it complete.  It's possible to pass most of the time"
    	echo "		and only fail once in a while, so we run the whole"
    	echo "		thing multiple times by default."
    	fi
    	echo "		Default: 20"
    	echo "	-m "
    	if [ -n "$HELP" ]; then
    	echo "		How many megabytes does the uncompressed tarball use on"
    	echo "		the filesystem.  We assume a roughly 75% compression"
    	echo "		ratio in the compressed tarball if the compression used"
    	echo "		is gzip, and 80% if the compression is bzip2.  So we"
    	echo "		take 4 or 5 times the size of the file depending on the"
    	echo "		file extension."
    	fi
    	echo "		Default: 4 * sizeof source .gz files,"
    	echo "			 5 * sizeof source .bz2 files"
    	echo "	-c "
    	if [ -n "$HELP" ]; then
    	echo "		We normally just calculate how many copies of the"
    	echo "		tarball to extract in order to be roughly 1.5 times"
    	echo "		physical memory size, but you can pass in a number if"
    	echo "		this doesn't work for some reason."
    	fi
    	echo "		Default: physical ram size * 1.5 / megs_per_copy"
    	echo "	-p	Toggles whether or not we will extract and diff all the"
    	echo "		source trees in parallel or serial."
    	if [ -n "$HELP" ]; then
    	echo "		Most linux filesystems will be much faster when running"
    	echo "		tests serially.  It tends to bog the drives down when"
    	echo "		the heads have to seek back and forth a lot to satisfy"
    	echo "		multiple readers/writers acting simultaneously.  But,"
    	echo "		parallel operations will tend to create much higher"
    	echo "		memory pressure and can be useful testing the virtual"
    	echo "		memory subsystem, so it's available as an option here."
    	fi
    	echo "		Default: serial"
    	echo "	-i	Just parse the arguments and say what figures we came"
    	echo "		up with and then exit."
    	exit 1
    }

clean_exit()
    {
    	# Kill any children that might be in the background, as well as any
    	# currently running foreground apps, then cleanup, then exit
    	for job in `jobs -p`; do
    		kill -9 $job >/dev/null 2>&1
    		while [ -n "`ps --no-heading $job`" ]; do sleep .2s; done
    	done
    	echo -n "Waiting for all pipelines to exit..."
    	wait
    	echo "done."
    	echo -n "Cleaning up work directory..."
    	rm -fr memtest-work
    	echo "done."
    	popd
    	exit $1
    }

trap_handler()
    {
    	echo " test aborted by interrupt."
    	clean_exit 1
    }

while [ -n "$1" ]; do
    	case "$1" in
    	-u)
    		USAGE=1
    		shift
    		;;
    	-h)
    		HELP=1
    		shift
    		;;
    	-t)
    		TEST_DIR="$2"
    		shift 2
    		;;
    	-s)
    		SOURCE_FILE="$2"
    		shift 2
    		;;
    	-x)
    		[ $EXTRACT = yes ] && EXTRACT=no || EXTRACT=yes
    		shift
    		;;
    	-n)
    		NR_PASSES="$2"
    		shift 2
    		;;
    	-m)
    		MEGS_PER_COPY="$2"
    		shift 2
    		;;
    	-c)
    		NR_COPIES="$2"
    		shift 2
    		;;
    	-p)
    		[ $PARALLEL = yes ] && PARALLEL=no || PARALLEL=yes
    		shift
    		;;
    	-i)
    		JUST_INFO=1
    		shift
    		;;
    	*)
    		echo "Unknown option $1"
    		USAGE=1
    		shift
    		;;
    	esac
    done

[ -n "$USAGE" ] && usage

if [ ! -f "$TEST_DIR/$SOURCE_FILE" ]; then
      echo "Missing source file $TEST_DIR/$SOURCE_FILE"
      usage
    fi

BZIP2=`file -b "$TEST_DIR/$SOURCE_FILE" | grep bzip2`
    if [ -n "$BZIP2" ]; then
    	COMPRESS_RATIO=6
    	COMPRESS_PROG=`which pbzip2 2>/dev/null`
    	[ -z "$COMPRESS_PROG" ] && COMPRESS_PROG=`which bzip2 2>/dev/null`
    else
    	COMPRESS_RATIO=4
    	COMPRESS_PROG=`which gzip 2>/dev/null`
    fi

# Guess how many megs the unpacked archive is.
    if [ -z "$MEGS_PER_COPY" ]; then
      ARCHIVE_SIZE_MB=$(ls -l --block-size=$MB "$TEST_DIR/$SOURCE_FILE" | awk '{ print $5 }')
      EXTRACTED_SIZE_MB=$(echo "$ARCHIVE_SIZE_MB * $COMPRESS_RATIO" | bc)
    fi

# How many trees do we have to unpack in order to make our trees be larger
    # than physical RAM?  We shoot for 1.5 times physical RAM size just to be
    # sure we unpack plenty and to compensate in case our estimate of unpacked
    # size is inaccurate. 
    if [ -z "$NR_COPIES" ]; then
      MEM_TOTAL_MB=$(free -m | awk '/^Mem:/ { print $2 }')
      NR_COPIES=$(echo "$MEM_TOTAL_MB.000 * 1.500 / $EXTRACTED_SIZE_MB" | bc)
      MIN_FREE_DISK=$[ $MEM_TOTAL_MB + $MEM_TOTAL_MB ]
    fi

# Check for disk free space and bail if we don't have enough
    DISK_FREE_MB=$(df -B$MB $TEST_DIR | awk '!/^Filesystem/{ printf $2 }')
    DISK_FS_TYPE=$(df -T $TEST_DIR | awk '!/^Filesystem/{ print $2 }')

if [ $MIN_FREE_DISK -gt $DISK_FREE_MB ]; then
    	echo "Error: Not enough free disk space in test directory"
    	echo "	Based on memory size of machine, you need at least"
    	echo "	$MIN_FREE_DISK MB of free space and you only have"
    	echo "	$DISK_FREE_MB MB at the moment.  Please free up"
    	echo "	disk space or set TEST_DIR to a directory on a"
    	echo "	filesystem that has enough free space to run the test."
    	echo
    	JUST_INFO=1
    fi

echo "TEST_DIR:		$TEST_DIR"
    echo "DISK_FREE_MB:			$DISK_FREE_MB"
    echo "DISK_FS_TYPE:			$DISK_FS_TYPE"
    echo "SOURCE_FILE:			$SOURCE_FILE"
    echo "COMPRESS_PROG:				$COMPRESS_PROG"
    echo "COMPRESS_RATIO:				$COMPRESS_RATIO"
    echo "ARCHIVE_SIZE_MB:			$ARCHIVE_SIZE_MB"
    echo "EXTRACTED_SIZE_MB:			$EXTRACTED_SIZE_MB"
    echo "MEM_TOTAL_MB:		$MEM_TOTAL_MB"
    echo "NR_COPIES:			$NR_COPIES"
    echo "NR_PASSES:		$NR_PASSES"
    echo "PARALLEL:		$PARALLEL"
    echo "EXTRACT:		$EXTRACT"
    echo
    if [ -n "$JUST_INFO" ]; then
      exit 0
    fi

# OK, options parsed and sanity tests passed, here starts the actual work
    pushd $TEST_DIR

# Set our trap handler
    trap 'trap_handler' 2 9 15

# Remove any possible left over directories from a cancelled previous run
    rm -fr memtest-work

# Unpack the one copy of the source tree that we will be comparing against
    echo -n "Creating comparison source..."
    if [ $EXTRACT = yes ]; then
      mkdir -p memtest-work/original
      $COMPRESS_PROG -dc $SOURCE_FILE 2>/dev/null | tar -xf - -C memtest-work/original >/dev/null 2>&1 &
      wait
      if [ $? -gt 128 ]; then
        clean_exit 1
      fi
    else
      mkdir -p memtest-work
      $COMPRESS_PROG -dc $SOURCE_FILE > memtest-work/original 2>/dev/null &
      wait
      if [ $? -gt 128 ]; then
        clean_exit 1
      fi
    fi
    echo "done."

i=1
    while [ "$i" -le "$NR_PASSES" ]; do
      echo -n "Starting test pass #$i: "
      j=0
      echo -n "unpacking"
      while [ "$j" -lt "$NR_COPIES" ]; do
        if [ $PARALLEL = yes ]; then
          if [ $EXTRACT = yes ]; then
            mkdir -p memtest-work/$j
    	$COMPRESS_PROG -dc $SOURCE_FILE 2>/dev/null | tar -xf - -C memtest-work/$j >/dev/null 2>&1 &
          else
            $COMPRESS_PROG -dc $SOURCE_FILE > memtest-work/$j 2>/dev/null &
          fi
        else
          if [ $EXTRACT = yes ]; then
    	mkdir -p memtest-work/$j
    	$COMPRESS_PROG -dc $SOURCE_FILE 2>/dev/null | tar -xf - -C memtest-work/$j >/dev/null 2>&1 &
    	wait
    	if [ $? -gt 128 ]; then
    	  clean_exit 1
    	fi
          else
    	$COMPRESS_PROG -dc $SOURCE_FILE > memtest-work/$j 2>/dev/null &
    	wait
    	if [ $? -gt 128 ]; then
    	  clean_exit 1
    	fi
          fi
        fi
        j=$[ $j + 1 ]
      done
      if [ $PARALLEL = yes ]; then
        wait
        if [ $? -gt 128 ]; then
          clean_exit 1
        fi
      fi
      j=0
      echo -n ", comparing"
      while [ "$j" -lt "$NR_COPIES" ]; do
        if [ $PARALLEL = yes ]; then
          if [ $EXTRACT = yes ]; then
            diff -uprN memtest-work/original memtest-work/$j &
          else
            cmp memtest-work/original memtest-work/$j &
          fi
        else
          if [ $EXTRACT = yes ]; then
            diff -uprN memtest-work/original memtest-work/$j &
    	wait
    	if [ $? -gt 128 ]; then
    	  clean_exit 1
    	fi
          else
            cmp memtest-work/original memtest-work/$j &
    	wait
    	if [ $? -gt 128 ]; then
    	  clean_exit 1
    	fi
          fi
        fi
        j=$[ $j + 1 ]
      done
      if [ $PARALLEL = yes ]; then
        wait
        if [ $? -gt 128 ]; then
          clean_exit 1
        fi
      fi
      j=0
      echo -n ", removing"
      while [ "$j" -lt "$NR_COPIES" ]; do
        rm -fr memtest-work/$j &
        wait
        if [ $? -gt 128 ]; then
          clean_exit 1
        fi
        j=$[ $j + 1 ]
      done
      echo ", done."
      i=$[ $i + 1 ]
    done

clean_exit 0

http://people.redhat.com/~dledford/memtest.shtml

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How to test the memory on a running linux server?30.05.15

Information Epoch 1778967682