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Archive for January, 2005

HOWTO Add journalization on a filesystem in Solaris

January 31, 2005 Leave a comment
This article was first written in January 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/202).

Solaris supports journalization (aka logging) on UFS filesystems which allows for shorter reboot times after a crash.

To activate it, it is really simple:

Go edit /etc/vfstab and add the term logging in the last column (mount options) for the UFS filesystems you want.

On-access Virus Scan

January 19, 2005 Leave a comment
This article was first written in January 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/200).

On a Linux server, to scan files on access using ClamAV, you can use Clamuko or, if using Samba to access it, use samba-vscan.

Athlon Powersavings on Debian

January 10, 2005 Leave a comment
This article was first written in January 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/199).

On 2.4 kernels on Debian, there is a driver that enables better powersavings for AMD760MP and AMD-760MPX (usually found on multi-processors mainboards such as Tyan S2460, S2462 and S2469) chipsets: amd76x_pm. It also exists as patch for the 2.6 kernel, but as it is non-standard, it is not included in Debian kernels packages.

To use it, simply add the following line to the end of your /etc/modules

:

amd76x_pm

To load it without rebooting, simply type the following command as root:

# modprobe amd76x_pm

Warning: Doing this on a Tyan S2469 running Debian Sarge with kernel 2.4.27-1-k7-smp will result in hanging the machine!

Using Debian’s superior package management system (APT)

January 9, 2005 Leave a comment
This article was first written in January 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/197).

The Debian GNU/Linux FAQ – Chapter 6 – Basics of the Debian package management system

Tips on working with Packaging Commands on Debian Linux

Debian package management, distributions and the /etc/apt/sources.list file

Creating custom kernels with Debian’s kernel-package system

Debian’s APT is probably the best packaging system available today. The last relevant drawback, packages signing, has been fixed recently, and will be part of Etch and following.

In the meanwhile, let’s try to approach the «Beast».

APT is «just» a set of frontends to the underlying dpkg

So, some of the manipulations done using APT may benefit of using dpkg directly instead. For example, manipulating an already installed package or a package which is already available on the local filesystem.

APT is a set of tools including, but not limited to: apt-get, apt-cache and aptitude. Their main role is to search and retrieve packages and their dependencies and pass them to dpkg. Their configuration files are stored in /etc/apt/ on your favorite OS.

The sources of the packages are listed in /etc/apt/sources.list, which is therefore mandatory.

Using apt is pretty simple, once you get some basic rules: Use apt-get for retrieving (downloading or copying from a CD or other supported media), installing and removing packages. Use apt-cache for information about packages, like their existence or not in Debian, their names, descriptions, version numbers available, … Use aptitude for enhanced features over apt-get, which it basically builds upon.

But let’s see in practise

Searching a package based on keywords in the name or description of the package:

$ apt-cache search keyword1 keyword2

Check the package version available (from sources in sources.list)

$ apt-cache policy package_name

Show more information about the same package [1

]

$ apt-cache show package_name

Install it and all of its dependencies

$ sudo apt-get install package_name

[1] the same for a package already installed would be dpkg -l package_name

Categories: English, OSS Solutions, Tech Crunch Tags: ,

HOWTO Speedup your Debian GNU/Linux

January 5, 2005 Leave a comment
This article was first written in January 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/195).

Warning: This article is still work in progress.

You have to keep in mind that speed is somewhat relative. It is often just a question of personal feeling, especially for a desktop machine.

There are many ways to speed your Linux installation. Here, we will show how to do it on Debian Sarge+, but most tips should also improve performances on other distributions.

We will focus on a desktop install. Speeding up a server is also possible and most of the time the same tips apply.

Some tips can also be found here: Debian Wiki LinuxSpeedup and here: Optimizing Desktop Performance.

There are many aspects to the slowness:

  • Time to boot (only important if you need to often reboot or halt your machine)
  • Time to start an application
  • Speed of the applications (while running)
  • Speed of the network (even some application not especially network-oriented may suffer from a slow network)

Lets’s address each one at a time:

Time to boot

Time to start an application

  • Prelink the system
  • Reduce RAM usage or add physical RAM

If some swapping is involved, time to start an application is increased. So try to stop as many programs and services you can, or add physical RAM (which is often the cheapest solution, by far). To stop as many programs and services, many things are possible […] If RAM is available, it will automatically be used as disk cache by Linux. So, more you have free, less the following is important.

  • Improve the disks/filesystems access speed
    • Use SCSI or SATA disks
    • On IDE disks, use “hdparm”
    • With UNIX filesystem types (ext2, ext3, reiserfs, …) the access to the filesystem slows down when nearly full. Try to free some disk space if you feel this. There is no need for defragmentation, except on very busy filesystems (like many, many small files written and deleted all the time for months. An e-mail or newsgroup server for example).
    • Change the disks to newer, faster ones
    • Use RAID-1 (hardware or software) to span disk access to several disks/controllers
    • Use the best-suited filesystem for your usage. Some filesystem are reported being faster or simply more appropriate to some usages, try to use that.
  • Application poorly-written: Some applications do a lot of disk access without reason, you can trace that with the strace utility by starting your application “under” strace.

The interesting options of strace here are: “-e trace=file”, “-c”, “-T”. See manpage for more info.

  • Quickstarters: Some (mainly graphical) applications provide a quickstarter, or quicklauncher which preloads some libraries and/or executables for loading it much faster on consequent uses. Ex: OpenOffice.org and Mozilla.

Speed of the applications you use

  • Use an optimized kernel for your machine (Debian packaged, or even home-made which involves rebuilding your kernel)
  • Use optimized binaries or libraries, when several are available, or there are some improving an existing library.

Using package libc6-i686 [1] [2] comes immediately to mind.

  • Prefer native applications (try to avoid Java/Python/Mono/… applications when possible)
  • Give more or less priority to some programs by renicing them manually or automatically with AND

Speed of the network

  • Name resolution
  • Bandwidth
  • Round-trip

Architecture-specific remarks

  • use libc6-sparcv9(UltraSparc II) or libc6-sparcv9b(UltraSparc III) instead of libc6-i686
  • prelink does not work correctly on Sparc and Alpha yet

[1] this packages includes optimizations for any recent CPU and the Native POSIX Thread Library (NPTL) support

[2] Be careful though, it can cause problems with some proprietary software, like some JDK. You would immediately notice though, and removing the package is enough to make it work again, may that be the case

Categories: English, Tech Crunch Tags: , ,
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