There is a dd test that floats around the PostgreSQL lists, so I wrote
this simple script to automate it - use at your own risk!
#!/bin/bash
# do something which parses command line parameters
DEFAULT_BLOCK=8
DEFAULT_PATH=/data/tmp
DEFAULT_FILE=ddfile
helpme()
{
echo "Usage: $0 [RAM=x] [PATH=/foo/bar] [FILE=foo] [BLOCKSIZE=X]"
echo "Runs a dd test on disk subsystem to benchmark I/O speed"
echo " BLOCKSIZE - given in K. Should be no need to change"
echo " default is 8 which is what PostgreSQL uses"
echo " RAM - must be specified in Gigs"
echo " default is to use output of 'free' command"
echo " PATH - where do you want the files created? i.e.
which filesystem do you want tested?"
echo " default is $DEFAULT_PATH"
echo " FILE - file name to create in test. Really makes no
difference."
echo " default is $DEFAULT_FILE"
exit 1
}
default_ram()
{
MYB=`free | grep Mem: | awk '{print $2}'`
((MYG=MYB/1000/1000))
export MYGIGS=$MYG
echo "RAM not specified - assuming ${MYB}/${MYGIGS}G"
}
default_path()
{
export MYPATH=$DEFAULT_PATH
echo "PATH not specified - using default $MYPATH"
}
default_file()
{
export MYFILE=$DEFAULT_FILE
echo "FILE not specified - using default $MYFILE"
}
default_block()
{
export MYBLOCK=$DEFAULT_BLOCK
echo "BLOCKSIZE not specified - using default $MYBLOCK"
}
RAMGIVEN=0
PATHGIVEN=0
FILEGIVEN=0
BLOCKGIVEN=0
while [ $# -gt 0 ]
do
MYVAR=`echo $1 | awk -F= '{print $1}'`
MYVAL=`echo $1 | awk -F= '{print $2}'`
case $MYVAR in
BLOCKSIZE)
MYBLOCK=$MYVAL
BLOCKGIVEN=1
;;
RAM)
MYGIGS=$MYVAL
RAMGIVEN=1
;;
PATH)
MYPATH=$MYVAL
PATHGIVEN=1
;;
FILE)
MYFILE=$MYVAL
FILEGIVEN=1
;;
-h|-help|--h|--help)
helpme
;;
*)
echo "ERROR : unknown parameter [${MYVAR}]"
;;
esac
shift
done
[[ $RAMGIVEN -eq 0 ]] && default_ram
[[ $PATHGIVEN -eq 0 ]] && default_path
[[ $FILEGIVEN -eq 0 ]] && default_file
[[ $BLOCKGIVEN -eq 0 ]] && default_block
PATH_EXISTS=0
[[ -d $MYPATH ]] && PATH_EXISTS=1
echo "[$MYGIGS][$MYPATH][$MYFILE][$PATH_EXISTS]"
mkdir -p $MYPATH
pushd $MYPATH
df .
FREESPACE=`df . | tail -1 | awk '{print $4}'`
BLOCKSPERGIG=125000
((ONCERAM=BLOCKSPERGIG*MYGIGS))
((TWICERAM=2*BLOCKSPERGIG*MYGIGS))
((THRICERAM=3*BLOCKSPERGIG*MYGIGS*MYBLOCK))
echo "Have:$FREESPACE, Need:$THRICERAM (3x RAM)"
if [ $THRICERAM -ge $FREESPACE ]
then
echo "ERROR: not enough room on disk"
echo "Have:$FREESPACE, Need:$THRICERAM (3x RAM)"
exit 2
fi
DDCOM="dd if=/dev/zero of=${MYFILE} bs=8k count=${TWICERAM} && sync"
echo $DDCOM
time sh -c "$DDCOM"
DDCOM="dd if=/dev/zero of=${MYFILE}2 bs=8K count=${ONCERAM}"
echo $DDCOM
$DDCOM
DDCOM="dd if=${MYFILE} of=/dev/null bs=8k"
echo $DDCOM
time $DDCOM
rm -f ${MYFILE}
rm -f ${MYFILE}2
[[ $PATH_EXISTS -eq 0 ]] && rmdir $MYPATH
popd
--
“Don't eat anything you've ever seen advertised on TV”
- Michael Pollan, author of "In Defense of Food"
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