Posts

Showing posts from January, 2015

No Site VPN for Cloud Data Centers

Image
A site to site VPN is the standard solution for connecting several physical data center locations. Going to the Cloud, the first idea that comes to mind is to also connect the Cloud "data center" with a site VPN to the existing physical data centers. All Cloud providers offer such a feature. But is such a VPN infrastructure also a "good idea"? Will it help us or hinder us in the future? I actually believe that for having many data centers a site VPN infrastructure is a dangerous tool. On the good side it is very convenient to have and to set up and it simplifies a lot of things. On the other side it is also very easy to build a world-wide mesh of dependencies where a VPN failure can severly inhibit data center operations or even take down services. It also lures everybody into creating undocumented backend connection between services. The core problem is in my opinion one of scale. Having a small number (3 to 5) of locations is fundamentally different from h

PPD - Pimp your Printer Driver

Image
I recently got myself a new printer, the HP Officejet Pro X476dw . A very nice and powerful machine, it can not only print double sided but also scan, copy and send faxes. And of course it has very good Linux support, thanks to the HP Linux Printing and Imaging Open Source project. On my Ubuntu 14.10 desktop everything is already included to use the printer. However, the first printouts where very disappointing. They looked coarse and ugly, much worse than prints from my old HP LaserJet 6 printer. After overcoming the initial shock I realized that only prints from my Ubuntu desktop where bad while prints over Google Cloud Print where crisp and good looking. So obviously something has to be wrong with the printer drive on Ubuntu! After some debugging I was able to trace this down to the fact that by default CUPS converts the print job to 300 dpi PostScript before giving it to the hp driver, as it shows in the CUPS logs: D [Job 261] Printer make and model: HP HP Officej

Comparing Amazon Linux

Image
Since ImmobilienScout24 decided to migrate to a public cloud I have been busy looking at various cloud offerings in detail. Amazon Web Services  (AWS) has a special feature which is interesting: Amazon Linux is a fully supported, "RHEL like", RPM-based Linux distribution. While not beeing a true Red Hat Enterprise Linux clone like CentOS or Scientific Linux (which is the standard OS for the ImmobilienScout24 data centers), it is derived from some Fedora version and comes with a nice choice of current software. To me it feels like "RHEL +" because so far all our internal stuff worked well but a lot of software packages are much newer than on RHEL 6 or RHEL 7. The 2014.09 release  updated a lot of components to very recent versions. On the other hand, we also found packages missing from Amazon Linux, most notably desktop-file-utils . This package is required to install Oracle Java RPMs . I found a thread about this on the AWS Forums and added a request fo