Recommended minimal amount of free space to keep?

[Ivan Baldo]

     Hello.
     So, LVM is cool, having different partitions for different stuff is 
cool, and of course Ext4 is cool and *reliable*.
     So, we create some logical partitions and put ext4 on them, 
reserving LVM space for growing those partitions or even making new ones 
later.
     The thing is, I would like to keep every filesystem as small as it 
can be, but without degrading the performance too much.
     I guess that having a filesystem 99% full will create too much 
fragmentation and many other issues, but having them only 30% full seems 
like a waste.
     Currently I try to keep them at 70% full utilization but I have not 
based that on anything just guess.
     So, what % hysteresis do you recommend? For example, when they get 
70% full then grow them so that they get 50% full? Other values?
     Thanks for the hints!
     Good day everyone.

-- 
Ivan Baldo - ibaldo at adinet.com.uy - http://ibaldo.codigolibre.net/
 From Montevideo, Uruguay, at the south of South America.
Freelance programmer and GNU/Linux system administrator, hire me!
Alternatives: ibaldo at codigolibre.net - http://go.to/ibaldo