Optimizing Debian for SSD storage
20. November 2013

The default I/O scheduler is optimized to schedule requests in an equal manner. Since SSDs are even faster in reading than writing, deadline scheduler favours read requests. This helpts to increase the throughput in some circumstances.

Debian based OpenVPN Router Applicance
16. November 2013

I use PC Engines Alix boards as VPN Appliances intended to connect some branch offices. They are rock solid, work for years without any problem and bring the flexibility one needs to implement all the nice stuff. 3x Lan Interface, 2x USB, passive cooling. Quite nice. Complete sets are available on Amazon or at some […]

Debian locale settings
6. November 2013

After installing a minimal debian-base distro like voyage-linux, there is a message like the following during updates f.e. figuring that there are some language settings to be done: perl: warning: Falling back to the standard locale (“C”). perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = […]

As mentioned before we run a four-node cluster for redundancy and charding. A pair of two nodes persists all metrics. To see if there is anything wrong, there is a monitoring check testing for double metrics, where they shouldn’t be. One day we got an alert reporting 20 double metrics. After some research we found […]

Reindexing owncloud 5 datastore
24. September 2013

After moving or adding some files manually, you may want to update the owncloud file cache, to making changes visible in the webinterface. While there was an app called “rescan_fs” to do so in owncloud 4, it is not working in owncloud 5. But there is a nice console command being able to do the […]

Wave Deploying a Graphite Cluster
20. September 2013

After building a graphite cluster being able to handle a huge amount of metrics, there is some maintenance to be done on it. Updates, config-changes and so on. No problem so far but if there is a need for nearly 100% of uptime, some tricks are necessary.

Graphite Scale Out
20. September 2013

Graphite is a toolset for distributed metric collection from nearly infinite sources. After some month of beta-testing graphite we decided to make it the backend for a new monitoring architecture, measuring nearly everything but alarming only on some of the metrics. This prevents redundant data gathering and enables to do really nice stuff like self-learning anomaly detection on this huge amount of metrics.


If you need to have a private alternative to hosted-services like dropbox, there are several solutions getting into place. After testing nearly all of them, I would say that TeamDrive is the best for my purpose.

Zarafa – Online Password Change
5. June 2013

I wanted to have a minimal and simple possibility to let the users change their passwords themselfs for zarafa. Best would be to have it as a webpage. I found a nice discussion about it here. Thus the php code from samu is made for Zarafa 6, I can validate that it is also working […]