On the previous week-end, Dotdeb’s website went down due to configuation problems. Sorry for that, it is now fixed.
I just updated Qmailadmin 1.2.11 for Etch amd64/i386 to include some changes :
- instead of a checkbox to enable/disable spam filtering on pop accounts, there is now a list to chose what to do (no filtering, marking spams, deleting spams, learn spam, learn ham). This allow anyone to easily train your bayesian filters.
- Spamassassin is now recommanded and will replace bogofilter in a near future
- Clamassassin replaces clamfilter.pl due to performance issues. Please DO update the /etc/procmailrc-* files during the upgrade to ensure virus are scanned.
I often receive emails telling me that Dotdeb is a great tool, but that some useful packages are missing, such as some PECL extensions. I wish I could maintain many and many packages, but I don’t think it’s a good idea for the Dotdeb’s overall quality and for my free time 😉 Sorry for that.
Then, this article will show you how to build packages from your favorite PECL extensions in a strict Debian way, using the dh-make-php package.
Vpopmail 5.4.25 has been packaged for Etch amd64/i386 to fix some annoying bugs. It’s safe and recommanded to upgrade your servers to this version.
For more information, read the official Changelog.
You can :
Volatile is now part of the Debian project and will be activated by default on Debian Lenny. Its goal is to provide up-to-date packages of some specific pieces of software (ClamAV, Spamassassin for example). Please use it instead of Dotdeb for your mail-filtering packages.
Just a little tip :
By default, Qmail listens to all the available IP address on the machine (0.0.0.0). It is possible to change this behaviour to bind Qmail to a specific IP.
We suppose that you are using Qmail from Dotdeb and launching it using the provided init script, /etc/init.d/qmail. Just edit it and change these lines :
sh -c "start-stop-daemon --start --quiet --user qmaild \ --pidfile /var/run/tcpserver_smtpd.pid --make-pidfile \ --exec /usr/bin/tcpserver -- -H -P -R -l 0 \ -u `id -u qmaild` -g `id -g nobody` -x /etc/tcp.smtp.cdb 0 smtp \ $rblsmtpd /usr/sbin/qmail-smtpd 2>&1 \ | $logger &"
by those ones :
sh -c "start-stop-daemon --start --quiet --user qmaild \ --pidfile /var/run/tcpserver_smtpd.pid --make-pidfile \ --exec /usr/bin/tcpserver -- -H -P -R -l 0 \ -u `id -u qmaild` -g `id -g nobody` -x /etc/tcp.smtp.cdb xxx.xxx.xxx.xxx smtp \ $rblsmtpd /usr/sbin/qmail-smtpd 2>&1 \ | $logger &"
(Just replace xxx.xxx.xxx.xxx by your IP address)
Now, when you list your listening dameon, you should see tcpserver listening to xxx.xxx.xxx.xxx:25 instead of 0.0.0.0:25.
machine# netstat -apn Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 xxx.xxx.xxx.xxx:25 0.0.0.0:* LISTEN 21175/tcpserver
TCMalloc is faster than the glibc 2.3 malloc (available as a separate library called ptmalloc2) and other mallocs that I have tested. ptmalloc2 takes approximately 300 nanoseconds to execute a malloc/free pair on a 2.8 GHz P4 (for small objects). The TCMalloc implementation takes approximately 50 nanoseconds for the same operation pair.
Its deployment in your LAMP stack can speed up your MySQL servers, since it enhances memory allocation on threaded applications with the downside of larger memory footprints.
Here is how to use it easily…
First of all, be sure you use Debian 5.0 (a.k.a. “Lenny”) or later. Then install the minimal tcmalloc library from Dotdeb :
apt-get install libtcmalloc-minimal0
Then, since the mainstream MySQL packages are not compiled against tcmalloc, you’ll have to trick your OS’ dynamic linker by adding the following line at the top of your /etc/init.d/mysql init script :
After relauching your MySQL server using the modified init script, you’ll take profit from tcmalloc’s faster memory allocation.
At the time of writing this article, I didn’t make benchmarks, but some reported that they had a ~15-20% performance gain. Please leave comments about your experience.
If Dotdeb is useful for you and if you want to mirror it, just add a cron job to periodically fetch the packages :
rsync -a --delete rsync.dotdeb.org::packages/ /your/local/path/
Note 1 : mirroring once a day should be enough. More frequent updates could lead to a ban without any warning.
Note 2 : Using anything else than Rsync (Wget, HTTrack…) could lead to a ban without any warning.
Using PHP sessions can be a problem when your PHP applications are load-balanced on many web servers. You can store them on a NFS export or recode the session_set_save_handler using a SQL backend for example. But there is no solution more efficient, more scalable, more performant and easier to deploy than using memcached…
Memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load…
Many well-known huge architecture (Facebook, Livejournal, Youtube…) are using it as memory caching to reduce the load on their servers. It can also be used to share PHP sessions among several servers. Let’s see how…
The first thing is to install the memcached server on your Debian server :
apt-get install memcached
Then, since the memcache PECL extension now provides its own session handler, it’s easy to plug PHP and memcached servers. Just install the appropriate extension (from Dotdeb) :
apt-get install php5-memcache
and change some of your PHP settings :
session.save_handler = files ; session.save_path = "N;/path"
session.save_handler = memcache ; change server:port to fit your needs... session.save_path="tcp://server:port?persistent=1&weight=1&timeout=1&retry_interval=15"
That’s all! After relaunching your Apache2 server, your PHP sessions will be stored on the memcached server.