Re: [SLUG] Synchronising file servers

[Grant Parnell <gripz@xxxxxxxxxxxxxx>]

On Wed, 20 Feb 2002, Frode Egeland wrote:

> Hi Sluggers,
> 
> I want to set up multiple file servers (SAMBA) in different regions of the
> world, and have them mirror each other's contents.
> 
> Has anyone done something similar, and if so, how? :)
> 
> (The traffic between them will be going through a VPN tunnel)
> 

Technically possible - rsync.

The big question is how are you going to resolve contention if people 
update files at the same time? Basically you're going to have to decide 
who owns a given area such that only one server allow's it's samba clients 
to update it. Having other people read the files is not an issue. 

One idea to toy with is handing over a symlink into a writable area, the
symlink would be like a token or batton in a relay race, there should only
ever be one.

server1				server2
/read/sales-figures		/read/sales-figures
/read/accounts			/read/accounts
/read/products			/read/products
/write/products (symlink)

On each samba server you only allow write access to the /write directory.  
In this example the /write/products symlink (which points to
/read/products) is handed over to a particular server.

Now you can essentially run an rsync every 5 minutes or so from each 
server with a /write directory.

Alternately, it may be possible to hook into samba much like you can with 
print jobs and have a script run each time a file is updated.

If you're thinking of doing anything with files that tend to get held open 
or are databases (eg MS Access) then samba is not the answer, you should 
re-think the problem.

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