Hetzner vServer VQ12 Review

Background

Hetzner has a reputation in the hosting industry for offering fast servers for a low price while still keeping a good quality. They seem to be able to do so by only offering few products with few configuration options and by building their own servers based on desktop hardware.
I was very interested to hear that they now also offer virtual servers based on Linux KVM. They currently do not charge a set up fee so I decided to give it a try. Continue reading “Hetzner vServer VQ12 Review”

BackupPC on Ubuntu 10.10 Maverick

Update: The instructions below will also work for newer versions of Ubuntu, e.g. Ubuntu 12.04 LTS.

There are a lot of server backup solutions out there and if you only manage a few servers chances are high that you are using your own scripts based on rsync and mysqldump to backup your machines. Well, you could have it so much easier. BackupPC is easy to install and configure and probably your only question will soon be “Why didn’t I use it earlier?”.
Continue reading “BackupPC on Ubuntu 10.10 Maverick”

find files that changed in the last day

If you want to find all files that have changed in the last day you can use the command

find / -mtime -1

If you run a server and want to monitor the file system and get a daily email with the list of files that were changed in the last 24 hours you can just add this as a cron job. The following example added to your crontab will scan your /var/www folder and send an email to user@example.com.

#  minute (0-59),
#  |   hour (0-23),
#  |   |   day of the month (1-31),
#  |   |   |   month of the year (1-12),
#  |   |   |   |   day of the week (0-6 with 0=Sunday).
#  |   |   |   |   |    commands
   0   0   *   *   *    find /var/www/ -mtime -1 | /usr/bin/mail -s "list of changed files" user@example.com

Adjust as needed.

 

KVM virtual machine hangs

If your KVM virtual machine crashes in Ubuntu 10.04 LTS because it is out of memory try to increase the assigned memory first. If that does not help, you can try to add these two lines to /etc/sysctl.conf (don’t forget to restart your computer for the changes to become effective).

vm.overcommit_memory = 2
vm.overcommit_ratio = 80

This reduces the risk of memory overcommitment and made my virtual machines run stable again. Before Apache and MySQL crashed under load, the log file would only show “apache2 invoked oom-killer”.

Here the article that pointed me in the right direction: http://opsmonkey.blogspot.com/2007/01/linux-memory-overcommit.html

And here a page that explains more about Linux and memory usage: http://www.win.tue.nl/~aeb/linux/lk/lk-9.html