[PD] [OT] slightly: building audio computer with PD

Mathieu Bouchard matju at artengine.ca
Wed Jan 2 23:42:01 CET 2008

On Wed, 2 Jan 2008, Derek Holzer wrote:

> The whole idea of read-only is for two reasons:
> 1) To protect the HD in case of unexpected shutdowns (which could happen
> nightly in a typical museum situation)

The whole idea of a separate volume for /var that you see on Linux, and 
the whole idea of /var in the first place, is to allow the rest of the OS 
to be mounted read-only. (networked volumes were an afterthought added in 
the 80's, though it fits really well with the /var concept).

The logs normally go in /var. It's much quicker to do an integrity check 
on the /var volume than on the whole OS, plus it ensures that the OS won't 
panic like some Linuxes do when the / volume was improperly unmounted. On 
OSes that don't have that latter problem, it's still a good idea because 
then you're sure that a fuckup in /var won't affect any of the files on 
the / volume.

If you don't have a separate /var, you can still do the same using e.g. a 
USB flash volume or old USB hard disk, for all your logs. In general it's 
a good idea to keep logs of what's going on in your installation, to 
improve diagnostic when a problem occurs.

E.g. I used logs to detect a very slow memory leak, that would take two 
weeks to notice. By looking at the rate at which it occurred, I was able 
to guess the data type of the leaked memory! (this was before Valgrind 
made it easier to debug those). Even if you don't program, it's cool to be 
able to give those details in a bug report.

Also the logs can measure the time between crashes and report it, or even 
the consistency of framerate, etc.

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| Mathieu Bouchard - tél:+1.514.383.3801, Montréal QC Canada

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