Is posible to tune HDD performance under linux?

[fzabkar]

Re: Is posible to tune HDD performance under linux?

I haven't used Linux in a very long time, so I can't help you. In any case I would think that a 3Ware or Linux forum would be better for these kinds of questions.

[hikaruichijo]

Re: Is posible to tune HDD performance under linux?

Well, the problem is the 3ware card, and I've found a lot of other forums talking about the poor performance of these cards and didn't found a solution, in my case the cheap sil3112a is a lot faster. Maybe that's why 3ware was bought by another company, bad products... In my case, I'll stay as far as I can from 3ware/amcc products from now and get another card when I can, I'm almoust sure a cheapo sil3114 would perform a lot better.

In any case I'm using this script, I didn't write it, so no credit for the work, only modified it a bit for my needs.

#!/bin/bash

START=0
INCREMENT=16
ALLOWDRIFT="50.0"

speed=0
try=$(( $START - $INCREMENT ))
keepgoing=true
topspeed=0
topra=0
answer=""
#echo "Enable 3Ware cache"
#tw_cli set cache c2 u0 on
#tw_cli set cache c2 u1 on
#tw_cli set cache c2 u2 on
#tw_cli set cache c2 u3 on
#echo "OK"
echo "Wich drive to test? (sda,sdb,sdc)"
read answer
echo "Start value?"
read value
try=value
echo "Testing $answer"
while [[ "${keepgoing}" == "true" ]]; do
try=$(( $try + $INCREMENT ))
echo "Top speed is ${topspeed} MB/sec at ${topra} readahead."
echo -n "Trying $try readahead..."
blockdev --setra $try /dev/$answer
speed=$(hdparm -t /dev/$answer | tail -n 1 | awk '{print $11}')
echo -n " ${speed} MB/sec"

# Hmm...
if [ "$(echo "scale=3; ${speed} > ${topspeed}" | bc )" -eq '1' ]; then
echo -e "\t** TOP SPEED"
topspeed="${speed}"
topra="${try}"
keepgoing=true
else
percdiff=$(echo -e "scale=3\n100 - ( ( ${speed} / ${topspeed} ) * 100 )\nquit" | bc)
if [ "$(echo "scale=3; ${percdiff} < ${ALLOWDRIFT}" | bc)" -eq '1' ]; then
echo -e "\t${percdiff}% slower"
keepgoing=true
else
echo -e "\t${percdiff}% slower, bailing..."
keepgoing=false
fi
fi

done

echo -e "Looks like the best speed of ${topspeed} MB/sec is achieved with a readahead of ${topra}.\n"



It works for any drive/controler so it may be usefull for anyone that want to improbe the performance of their hdds under linux.