IIRC there may be as many as 40 linodes on a 360 host, all sharing the same disks. I don't think 4.8M/s is unreasonable if you consider the probability that many other linodes are accessing the disk at the same time.

@arjones85:

1048576000 bytes (1.0 GB) copied, 217.374 seconds, 4.8 MB/s
How exactly were you creating the file?

Just used dd.

Here's the script in its entirety:

! /bin/sh

Author: chriss

Date: 2008/09/13

Simple benchmarks

TFILE=./ddtmp

TFILEGZ=${TFILE}.gz

SRCFILE=/dev/urandom

NULL=/dev/null

GREPBIN=which grep

WBIN=which w

HEADBIN=which head

MD5SUMBIN=which md5sum

TAILBIN=which tail

GZIPBIN=which gzip

DDBIN=which dd

DATEBIN=which date

TEEBIN=which tee

Quick sanity checks

if [ ! "$GREPBIN" ]; then

echo "Utility grep not found. Exiting."

exit 1

fi

if [ ! "$WBIN" ]; then

echo "Utility w not found. Exiting."

exit 1

fi

if [ ! "$HEADBIN" ]; then

echo "Utility head not found. Exiting."

exit 1

fi

if [ ! "$MD5SUMBIN" ]; then

echo "Utility md5sum not found. Exiting."

exit 1

fi

if [ ! "$TAILBIN" ]; then

echo "Utility tail not found. Exiting."

exit 1

fi

if [ ! "$GZIPBIN" ]; then

echo "Utility gzip not found. Exiting."

exit 1

fi

if [ ! "$DDBIN" ]; then

echo "Utility dd not found. Exiting."

exit 1

fi

if [ ! "$DATEBIN" ]; then

echo "Utility date not found. Exiting."

exit 1

fi

if [ ! "$TEEBIN" ]; then

echo "Utility tee not found. Exiting."

exit 1

fi

Do a simple benchmark

LOGFILE="./${0}.$DATEBIN +%Y%m%d%H%M%S.log"

echo "Start: $DATEBIN "+%Y-%m-%d %H:%M:%S"" | $TEEBIN -a $LOGFILE

echo "Create a 1GB file." | $TEEBIN -a $LOGFILE

$WBIN | $HEADBIN -1 | $TEEBIN -a $LOGFILE

$DDBIN if=$SRCFILE of=$TFILE bs=1024 count=1024000 2>&1 | $TAILBIN -1 | $TEEBIN -a $LOGFILE

$WBIN | $HEADBIN -1 | $TEEBIN -a $LOGFILE

echo "gzip of 1GB file" | $TEEBIN -a $LOGFILE

{ time -p $GZIPBIN $TFILE 1>$NULL 2>&1 ; } 2>&1 | $GREPBIN real | $TEEBIN -a $LOGFILE

echo "md5sum of gzip 1GB file" | $TEEBIN -a $LOGFILE

{ time -p $MD5SUMBIN $TFILEGZ 1>$NULL 2>&1 ; } 2>&1 | $GREPBIN real | $TEEBIN -a $LOGFILE

rm $TFILEGZ

echo "End: $DATEBIN "+%Y-%m-%d %H:%M:%S"" | $TEEBIN -a $LOGFILE

I tried your script on two Linodes, a 360 and a 540.

360````
Start: 2009-10-12 19:36:35
Create a 1GB file.
19:36:35 up 98 days, 23:55, 3 users, load average: 0.00, 0.05, 0.09
1048576000 bytes (1.0 GB) copied, 219.067 s, 4.8 MB/s
19:40:14 up 98 days, 23:59, 3 users, load average: 1.54, 0.69, 0.33

540````
Start: 2009-10-12 18:00:24
Create a 1GB file.
 18:00:24 up 5 min,  2 users,  load average: 0.00, 0.00, 0.00
1048576000 bytes (1.0 GB) copied, 145.728 s, 7.2 MB/s
 18:02:50 up 7 min,  2 users,  load average: 1.47, 0.64, 0.24

Looks as if Stever may be right - in this rather limited test, the rate of disk I/O was definitely better with less 'nodes on the host. Does anyone with a bigger Linode have time to do the test?

@arjones85:

SRCFILE=/dev/urandom

(…)

$DDBIN if=$SRCFILE of=$TFILE bs=1024 count=1024000 2>&1 |
I think you will find that /dev/urandom is the speed limiting factor in this test. Quite a few CPU cycles go into reading from that device.

Indeed, /dev/zero is probably what you want to use for disk benchmarks.

Stever - you're correct - I just checked the script for 'naughties' before I ran it, didn't give much thought to what it was using as it's input.

Guzpaz - yep - using /dev/zero pumps the disk I/O rate up to 30.6 MB/s on a 360.

This command may be of interest to benchmark your disk speed:

hdparm -tT /dev/xvda