Tag Archives: debian

Quick and dirty fix for VMware Linux guests loosing clock accuracy

Posted on by

I covered on a previous post how to keep the clock synchronized for VMware Linux guest(s). Well this seems to not work at least for recent versions VMware Server 2 (i.e. the one with web based management console). For now the quick& dirty solution I am using is putting a cron job that executes ntpdate pretty often…

My cron job looks like this:

Yes, this fix requires to have NTPDATE installed (apt-get install ntpdate under Debian).

How to install MySQL Server on Debian Linux

Posted on by

While installing MySQL Server it is always good to keep in mind that the logs and data folders will potentially have a big size. By default MySQL keeps them in the root mount point (i.e. ‘/’). That may cause your database server system disk to get full, which is never a good idea.

This article describes how to move these two folders to ‘/home’ which is ideally mounted into another disk and has enough space to keep your database data and logs.

First, I install the required apt-get packages as follows:

To check the status:

Now, stop MySQL, move the folders to the right location, reconfigure MySQL and start again:

These are some settings that I usually put on the /etc/mysql/my.cnf configuration file:

For these changes to take effect, you would need to restart MySQL:

If you want to ignore databases or tables you may use the following options:

Having ‘binlog_ignore_db’ is enough to exclude databases from replication BUT having ‘replicate_ignore_db’ as well will make things clearer since the databases that are being ignored will appear in both the ‘SHOW SLAVE STATUS\G’ and ‘SHOW MASTER STATUS\G’.

KeepAlived Installation under Debian Etch

Posted on by

Briefly, KeepAlived is a daemon that is able to provide failover capabilities to servers/services by binding virtual IP addresses to machines. In the event of failure, KeepAlived would reassign this virtual IP to another machine. This action is executed fast (less than 2 seconds) and automatically.

This is a very interesting daemon to be used in combination with HAProxy, for example. It would be possible to have a failovered load balancer. In the event of this load balancer failing, keepalived would switch to another that is up and running in such a clean and fast way that the clients would not notice.

Installation steps under Debian Etch

The system will ask a couple of questions. I usually reply using the default values, then configure myself manually the daemon, by editing /etc/keepalived/keepalived.conf.

To make the virtual IP address bindable, you should add this line /etc/sysctl.conf:

Check binding:

It is convenient to alter the order when keepalived is being started upon restarts. We probably want to have it started at the end so all the services are already running by the time keepalive runs. To do that:

See Also

How to install NAGIOS NRPE plugin under Debian Linux

Posted on by

NRPE allows you to remotely execute Nagios plugins on other Linux/Unix machines. This allows you to monitor remote machine metrics (disk usage, CPU load, etc.). NRPE can also communicate with some of the Windows agent addons, so you can execute scripts and check metrics on remote Windows machines as well. Citation.

You may follow the steps to install NRPE in any of the following ways:

1) Steps (compiling from sources)

First, you should download the latest NRPE version from HERE.

Then, install some required packages:

Unpack the NRPE addons, configure and install:

2) Steps (using apt binaries)

Invocation
NRPE can now be invoked using the following:

Another option would be to create a symlink to make the invocation easier:

Thus:

Fixing VMWare vmxnet driver networking issues under Debian Linux

Posted on by

It seems that using particular combinations of VMWare Server and Linux Kernel version(s) while installing VMWare Tools under Linux guest machines, may render the virtual machine’s networking down.

This page provides a “hacky” workaround to solve this situation. There might be other deeper and more proper solutions out there but I came up with this one because it is very simple to put in place and not harmful at all.

So, let’s imagine this scenario:

  • VMWare Server 1.0.2 (other versions might apply as well, not tested thought)
  • Debian Linux 4.0 Etch guest, running 2.6.18-6-686 kernel (other versions might apply as well, not tested thought)
  • VMWare Tools 1.0.2-39867 (other versions might apply as well, not tested thought)

Then, after the VMWare Tools get installed, the screen shows something like this:

Right now the networking does not work. If you try to see what is going on, you should see something like this:

That’s it. No network interfaces. If you go for VMWare Tools’ installer suggested steps, the networking should work again:

E.g.:

The issue here is that this settings will be lost upon restart. I guess it is a matter of having the proper modules loaded properly but I have not been able to find the proper configuration files combination to get this reliably enough.

Proposed solution/workaround

Basically, create a simple script that does what VMWare Tools’ intaller suggests and have it invoked upon system restart.

The script should contain the following:

This file should be created under /etc/init.d folder, with 755 permissions (i.e. chmod 755 filename). The, to have it invoken upon restart you could do this:

I suggest having the initscript invoked with a lower sequence code (i.e. 10) so the networking gets activated before other services which may use and/or need it.

That’s it. Now your virtual machine’s networking should be fine upon restarts.

See Also