Overview of cloud services

Comparing all the cloud offerings is quite a challenge. Here the best resources I could find so far:

AWS Services by Amazon
AWS and Google by Google
AWS and Azure by Microsoft
AWS and rackspace by Rackspace
IBM Bluemix by IBM

And here some third party information:

AWS vs. Google vs. Azure by sitepoint.com
Azure vs. AWS by tomsitpro.com

Some other cloud service providers:

https://www.ovh.ie/ several DCs mainly IaaS and VDI
https://www.digitalocean.com/ several DCs and nice SaaS portfolio for developers
http://www.dimensiondata.com/Global/Solutions/Cloud several DCs for IaaS

Anything missing? Let me know and I’ll add it to the list.


How to recover lost files

I am assuming you do not use any disk encryption here, that would require another procedure to follow.

I use Ubuntu as OS.

First of all, if you lost an important file, stop using the file system the file was on NOW. The data you lost might still be on the disk, but the longer you use the file system, the higher the chances are that the data gets destroyed. So unmount that file system or switch the system off now.

I will show how data can be recovered that was on a 2GB USB stick, but in principle that works for HDs as well. It just takes much longer, and you need much more disk space for recovery.

First thing I do is that I create a disk image of the disk. That way I do not accidentally destroy any data that might still be there.

I have stored files on this stick and then reformatted the stick:



Now the file system does not know anything about the files anymore. However the data has not been overwritten and is still on the stick.

Lets try to recover them. I need to recover them the hard way, a simple undelete will not work.

I dump all data from the USB stick /dev/sdi to a file. This Step is essential. I am now working on a copy of the data and am not in danger to destroy the original data.

dd if=/dev/sdi of=USBimage.raw

OK, the data is in a secure place now.

No I try to recover the file. I use the carving tool foremost. Foremost scans the disk for known start and end markers of several file types.

I will now use foremost to reconstruct the file

foremost -i USBimage.raw -o foremostout

And like a miracle the file was reconstructed in foremostout/jpg/00007750.jpg

This works quite well for all files with a clear start and end marker. Look into the foremost man pages for more info.

A bit more effort is needed to restore a simple txt file. Here we have no clear start and end markers.

My favorite way is to extract the strings from the diskimage and then restore the files manually.

strings USBimage.raw > strings.txt

I open strings.txt with vi and find the text I was looking for “This text is very important to me.”

Good luck with recovering your data!

Private file sharing in the cloud

This week I was looking for an alternative to dropbox. Dropbox is fine for me as long as files are public and not in any way confidential. However some times I have a need to work together with colleagues and we don`t want to do so in privacy. So I was looking for a cloud service provider bases in Europe and with end to end encryption. The first I found was Wuala.

I am pretty sure there are more services like that around. Let me know if you know another one and I will add it to the article !!!

IBM® Redpaper™: Deploying IBM Flex System into a Cisco Network

Here a link I had on my blog before my server crashed ….

The IBM® Redpaper™ is released. Together with my colleagues from the Technical Expert Council, Central Region (TEC CR) we wrote this guide: Deploying IBM Flex System into a Cisco Network


Smarter City Rio de Janeiro

A few years ago I was in Brasil and browsed ridethehill.com the net to find some nice pictures and videos of Rio. I found this video on ibm.com and have to share it with you.

Rios controll system has some really nice features like

flood and landslide forecast
automated notifications to emergency personnel
weather forecast
updates available via Twitter @OperacoesRio

and Facebook at Centro de Operações Rio

and much more …

Here a second video that gives a bit more of an insight how the system is used.

Swarm of robots

With this swarm of robots my dream might come true one day. Well I guess it is a pretty common dream. A swarm of small cleaning robots! Wouldn’t that be brilliant? Hundreds of small helpers cleaning up when we are at work. OK, the vacuum robots we can buy today are not bad, but I want something than can clean on my desk and the windows as well.

Three ways to recover from WP server failure

So my server failed a few day ago. And if failed badly. All data lost, all posts gone … pretty much everything gone.

  1. The easiest way is just to restore your backups …. but when you are reading this article then you most likely do not have a backup.
  2. Use the WordPress export tool from time to time. It is under Tools -> data export This will cause you a lot of work in case you loose your data.
  3. One other way to get to your lost data is to use google cache. Just search on google for all webpages from your site. I searched for “site:rissmann.ch”. This will show all sites google knows about and you can use the little symbol next to the URL to access the google cache. Now starts the manual part, open all sites in the cache and save them. After that you can use the saved pages to rebuild your website.

As you might already suspect I had to use method three to rebuild my blog. And I am not jet finished. Still several articles I need to recover.




Android ScaleGestureDetector example

I spend  quite some time to work out how the ScaleGestureDetector on Android works.

However I could not find a good example on the net. So here I post my test code in the hope that it might be useful for someone else:

public class MyTextView extends TextView implements OnTouchListener,OnScaleGestureListener {
ScaleGestureDetector mScaleDetector = new ScaleGestureDetector(getContext(), this);
public MyTextView(Context context, AttributeSet attrs) {
super(context, attrs);
Log.d("MytextView", "MyTextView");
public boolean onScale(ScaleGestureDetector detector) {
Log.d("MytextView", "onScale");
return true;
public boolean onScaleBegin(ScaleGestureDetector detector) {
Log.d("MytextView", "onScaleBegin");
return true;
public void onScaleEnd(ScaleGestureDetector detector) {
Log.d("MytextView", "onScaleEnd");
public boolean onTouch(View v, MotionEvent event) {
Log.d("MytextView", "onTouch");
if(mScaleDetector.onTouchEvent(event)) return true;

return super.onTouchEvent(event);

The trick is to generate the ScaleGestureDetector and call it from the ontouch method. The Detector will then call the scale… methods if a ScaleGesture is detected. Now just register the OnTouch callback this object and you are done:

public class ScaleActivity extends Activity {
public MyTextView mytextview;
public ScaleGestureDetector scaledetector;

/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {

mytextview=(MyTextView) findViewById(R.id.TextView);
scaledetector=new ScaleGestureDetector(this, mytextview);

Pretty simple.