Re: Running several instances of an fs server...

[James Morrison]

--- marco@linuxrulez.nl wrote:
> > Hi!
> >
> > I'm wondering what happens when several instances of a filesystem
> > server (with the same device as a parameter) run on a machine? In other
> > words, what happens to the underlying data? How is data consistency
> > handled?
> 
> AFAIK this isn't handled at all. Why do you want to do this?
> 

 This can be handled.  There is no problem if you attach all the translators
in readonly mode, --readonly.  However, usually this doesn't do what you want.
Alternatively, I set one translator with --writable and all others with
--readonly.  I only use this for booting n-hurds where the writable filesystem
cleans itself up before I try to read from the readonly filesystem.

> > Since filesystems can be `mounted' in users directories, serveral users
> > of the same machine are very likely to mount the same filesystem in
> > their own home dir, so that's an important issue.
> 

 This isn't true because users currently cannot get the device master port
for the physical devicce.

> A user will not (in most cases) 'mount' a disk stored filesystem which is
> stored on a device or partition, for example (and it will not have the
> permissions to do this). The user can 'mount' a filesystem stored in a file
> (this is called a loopback device in linux).
> 
> Most users will only mount network filesystems or special purpose
> filesystems.
> 
> 
> 


=====
James Morrison
   University of Waterloo
   Computer Science - Digital Hardware
   2A co-op
http://hurd.dyndns.org

Anyone referring to this as 'Open Source' shall be eaten by a GNU

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