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Re: /run vs /var/run

Russell Coker <russell@coker.com.au> writes:

> On Monday 19 December 2005 11:49, Bernd Eckenfels <ecki@lina.inka.de> wrote:
>> In article <[🔎] 20051218210932.GD25848@boogie.lpds.sztaki.hu> you wrote:
>> > If /run is tmpfs, it means everything stored there eats virtual memory.
>> > So a musch metter strategy would be to move everything from /run to
>> > /var/run at the end of the boot process.
>> tmpfs stores run ressources in vm more efficiently (since they are
>> otherwise in th buffercache and the filesystem). And you cant really move
>> the run ressources. I vote for having run a tmpfs and having /var/run ->
>> symlinked to /run.
> tmpfs also doesn't require any writes to a disk.  Flash storage is getting 

But unlike a ramdisk it can be swapped. And virtual address space is
cheap, even on mips system with the little they have.

> larger and cheaper and we should expect that the number of systems with no 
> moving parts will keep increasing.  On such a system you want to put all the 
> small data that is written often on a RAM disk of some sort.  The Familiar 
> distribution (based on Debian and used on iPaQ hand-held machines) used RAM 
> disks for /var/run and many other things.
> I think it's generally a good idea to make the main Debian development tree 
> work well with flash storage whenever it doesn't hurt other areas of 
> performance.
> Also as for sym-links, there's no reason why /var/run couldn't be used all 
> along.  Imagine we have a system where /var is mounted from an LVM volume (or 
> something else that can't be mounted early on).  So we start with a /var 
> mount-point which has a /var/run mount-point under it and we mount our tmpfs 
> there.  We then use the --bind option of mount to have it also mounted 
> as /etc/run (or whatever).  Then we have daemons started etc which do things 
> under /var/run without any modification to their previous operation.  When 
> the real /var file system is mounted mount --bind or --move is used to put 
> the file-system back on /var/run from /etc/run.  Optionally we could have 
> special-case code in the script that does mount -a to have it umount /var/run 
> first.

Can't be umounted, files may be opened. And --move it just to have no
/run dir is pretty silly.

> I believe that this idea is significantly better than the /run suggestion.  It 
> requires changing no other programs, gives the potential of performance 
> benefits (RAM being faster than disk) and system reliability benefits on 
> flash storage systems, and doesn't require breaking the FHS.

Basicaly everything that needs /run doesn't use /var/run anyway,
e.g. mount. And one could link /var/run to /run on both / and /var and
then nothing needs to change even if it uses /var/run.


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