Oversized auxiliary file systems in Dapper; why?

[Tchize]

Urtzi Jauregi a écrit :
> 	Hello everybody,
>
> 	When I want to check the available space on my hard disk, I get the 
> following:
>
> urtzi at escher:~$ df -h
> Filesystem            Size Used Avail Use% Mounted on
> /dev/hda1             5.0G  3.5G  1.3G  74% /
> varrun                248M   88K  248M   1% /var/run
> varlock               248M  4.0K  248M   1% /var/lock
> udev                  248M  140K  248M   1% /dev
> devshm                248M     0  248M   0% /dev/shm
> /dev/hda3              64G   43G   18G  71% /home
>
> 	I am quite surprised by the four 248-MB filesystems. I have checked quite 
> often, and these filsystems are never more than 1% full.
>   
You hardrive use is only represented by the lines having /dev/hda

Those are mounted as tmpfs (type mount to get details on your mounts).
Detailed documentation on what is tmpfs can be found here:
http://www.mjmwired.net/kernel/Documentation/filesystems/tmpfs.txt, but
average user don't need to read it. You just have to know that it's a
temporary "in memory/swap" filseystem that grow and shrink to use only
the memory required by it's current content. You are so using a bit more
than 232K of memory for you tmpfs. Not a great deal. The "filesystem
size" is just the maximum size the tmpfs can use.
>  	How can I tweak the system to remove or make them smaller (I mean, does udev 
> need 250 MB to work at all?)? Do I actually need all of them?
>   
Considering my previous paragraph, am not sure you want to tweak this
:). Anyway, the default maximum size of a tmpfs is half of available RAM
memory (swap excluded). however you can change it by editing
/etc/default/tmpfs, just then read the doc about tmpfs before choosing a
size.
Does udev need 250M to work? not at all, but as tmpfs is not using less
memory if you change it's maximum size, it's not big deal. Your udev
currently use about 140k of memory.
Do you need them? Well question is, do you need such volatile data
stored on you hard disk and a script at startup to clean all the mess?
Or do you prefer those volatile data to just die along with power off?
> 	If it has to be like that, I'd like to know how do I get in exchange for 
> losing a whole GB of disk space! ;-)
>   
It's stored only in RAM, no hd space used (except in swap if those
little 140k get swapped out)
> 	It just occurred to me: maybe these four systems are another way to display 
> the swap partition? I have a 1 GB swap at /dev/hda2, but I can't see it here.
>   
To see your swap, don't use df, type
cat /proc/swaps
> 	Thanks in advance,
>
> 	- Urtzi -
>
>