Posts with the tag Speedup

Improving the Speed of Software Raid on Linux (Read/Write/Resync)

Speeding up the write access of a RAID array

echo 32768 > /sys/block/md0/md/stripe_cache_size

Source: Stackoverflow

Speeding up RAID1 array rebuild


echo 50000 > /proc/sys/dev/raid/speed_limit_min
echo 200000 > /proc/sys/dev/raid/speed_limit_max

the resync speed went from 1M/sec to about 25M/sec:

cat /proc/mdstat

Personalities : [raid1]
md1 : active raid1 sdb3[0] sda3[1]

Read on

Clear Cached Memory on Ubuntu

To clear the cache / cached memory (free pagecache, dentries and inodes) on Ubuntu or Debian you can write the value 3 to /proc/sys/vm/drop_caches:

# You should be the superuser ('root') or become the superuser:
sudo su
# Now sync filesystem and clear the caches:
sync && echo...

Read on

Usage of a Ramdisk on Linux

The older approach involves the creation of an ext3 filesystem on /dev/ram0 (a part of the RAM):

sudo mke2fs -t ext3 -m 0 -q /dev/ram0
sudo mkdir -p /media/ram0
sudo mount /dev/ram0 /media/ram0
sudo chown USERNAME /media/ram0
sudo chmod u+rwx /media/ram0

The newer and easier method to create a ramdisk is to make...

Read on

Clear inactive memory on Mac OS X

The purge command clears the inactive memory on Mac OS X. Simply run the command with no parameters:




Read on

Zombie Processes on Linux

Find zombie / defunct processes:

ps -ef | grep -i defunct

Kill them:

sudo ./ --admin

where is the following bash script by Markus Gattol:

#! /bin/bash
# Zombie processes killing script. Must be run under root.

case "$1" in

Read on

Custom DNS entries per domain (nice feature for VPN setups)

OS X has a good feature built in: the dns resolver. It allows you to specify different DNS servers for different domains. After creating the /etc/resolver directory, you can create a /etc/resolver/ file with nameserver in it to redirect DNS requests for this domain to that specific nameserver.



Read on

Temporarily Disable Spotlight Indexing

Temporarily disable Spotlight indexing is especially useful when connecting a large external HDD for the first time to copy/move/access some files as the Sportlight scanning slows down the drive access a lot.

sudo mdutil -a -i off

to turn it back on:

sudo mdutil -a -i on



Read on

Speed up your Ubuntu karmic system

  • enable preload: sudo apt-get install -y preload (more: Change settings using sudo gedit /etc/preload.conf and display the log file using sudo cat /var/log/preload.log. A more extensive state file can be accessed on: /var/lib/preload/preload.state.)
  • disable Pango smoothing on Firefox export MOZ_DISABLE_PANGO=1. Put this in your ~/.bash_profile or ~/.bashrc.
  • start...

Read on

Test Speed Of Partitions (and therefore also Hard Disk Drives)


The command sudo hdparm -t /dev/sda on my Samsung SpinPoint F1 HD103UJ returns:

 Timing buffered disk reads:  210 MB in  3.02 seconds =  69.63 MB/sec


Compile seeker (multithreaded) from seeker_baryluk.c using:

gcc -o seeker -O2 -march=native seeker_baryluk.c -pthread

And execute it like this (where the...

Read on

Short Of Disk Space - Find Large Files & Clear Caches

When your hard disk is getting full you might want to know why and what files are the largest. This post describes how to find that out and clean up using the disk usage analyser, package cache cleaning and a fast way to list big files on the terminal using...

Read on