falsche Fehler

Friday, January 13. 2012

 Daran kann man sich dusselig suchen: eine Anwendung gibt einen kryptischen, sehr spezifisch klingenden Fehler aus. Aber es ist im Grunde etwas ganz anderes...

VirtualBox ließ sich gerade bei mir überhaupt nicht mehr starten, Failed to create the VirtualBox COM object war die Msg und in den details stand: VirtualBox Error - Callee RC: NS_ERROR_FACTORY_NOT_REGISTERED (0x80040154)

Google liefert auf diese Fehlermeldung reichlich Hilferufe und Forenbeiträge, mit oder ohne "solved".  Reichlich Gelegenheit, fruchtlos im System herumzuwerkeln - hier war das Problem nämlich schlicht: Festplatte absolut vollgeschrieben. Ein Backup-Laufwerk war nicht gemounted und so lief die kleine Systempartition voll.
Ein weiteres Symptom war: Google Chrome startete nicht (ohne jegliche Fehlermeldung)

Eine komplett vollgeschrieben Systempartition kann in der Folge weitere Überraschungen bewirken, apt-get etwa vermochte bei einem folgenden update nicht, fehlerfrei eine neue kernel-version zu installieren. Es sei nicht genügend Platz auf /tmp. und df listete /tmp als overflow und zu 100% belegt. siehe: /etc/init.d/mountoverflowtmp

What to do when the root partition is full?

Snapper und SnapUtil

Tuesday, April 12. 2011

An earlier post described my TimeMachine-inspired SnapShot backup based on rsync and hard links downloadable there. It has been very useful for me already. You know how things can happen, I was working on a script which should empty a certain directory before writing new files there and at some point substituted the hard-coded path to that directory with a parameter, and then tested the thing forgetting to enter the path-parameter.
Thus, 
rm -rf $DEST_BASE/*  effectivly turned into 
rm -rf /*

I was so glad my last snapShot was but 70 min old.

Then I had to detail the steps and times of working on a certain project a posteriori, which files had been edited over what times on which days? A series of snapShots is basically a very good source for this kind of research, but in praxis it turned out to be uncomfortabel to always walk the pathes up and down between the parallel snapShot directories.

Typically the folders I wanted to compare always share a common relative path, like
snapShots/snap1/some/longish/and/winded/path 
snapShots/snap2/some/longish/and/winded/path 
snapShots/snap3/some/longish/and/winded/path 
and I soon started to wish I had symlinks to the destinations in a special folder. And while in some cases I want to see all the files, in other cases I'd rather only have the files that got changed between one snapShot and the next.

So I ended up creating a tool to build just this.

At the core this is a bash shell script which gets the pathes to the snapShot base, the relative path to link, the destination dir to place the symlinks in and then walks the file tree. It is supported by a gui front end that makes picking the pathes and setting the parameters so much easier.  

Together they form SnapUtil, based on Bash, Python_2.6 and wxPython. This is an early alpha version, GPL 2,  download .

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