[NTLUG:Discuss] File Replication & 2-way Synchronization

[Phil Guier]

How about setting up a Virtual Lan between your sites?
You would gain security, speed, stability and control,
and sync of the accounting program might have an
easier solution. I'm not an expert on VLans but I have
discussed this very scenario with a vendor that does
this all the time with companies. I don't want to
advertise for anyone here so if you want, email me and
I'll be glad to share with you any info I have. 

Phil 

--- Stan Tigrett <stigrett at killer-webs.com> wrote:
> 
> PROBLEM: We have 3 offices in different locations
> who need access to each of the other office's files.
>  The offices each run a linux/samba fileserver, with
> clients using win9x to connect.  Each office is
> connected to the internet via a ADSL line
> (1Mb/128kb) and run a linux firewall (a different
> machine than the fileserver).  One office has about
> 10 gigs of data, and the other two have about 2 gigs
> each.  The users can't handle using FTP - they will
> only accept a 'new drive mapping' in windows.  It is
> not very likely that the same file will be accessed
> by different users at different locations at the
> same time.
> 
> POSSIBLE SOLUTIONS:
> 1 - Mount the data remotely using NFS across the
> internet, using strict firewall rules to only allow
> exporting to the 3 office IP addresses.  Use samba
> to share the nfs mount to the users.
>  Pros -  Data will always be current.  Changes will
> occur in real time.
>  Cons -  The DSL links not very stable.  Would
> probably need a cron job to test the nfs connection
> & re-mount it if neccessary.
>   Data access will be extremely slow.
> 
> 2 - Use rsync to perform 2-way synchronization of
> the files, using the same strict firewall rules
> above...  Use samba to share the replicated
> directories.
>  Pros - Data access will be as fast as local data.
>   Don't have to worry about the DSL links
>  Cons -  Data may be stale.
>   Initial replication will take a long time...
>   Deleting files from one server to the other...
> 
> It seems that #2 is the best solution so far, using
> a cron job to synchronize the files every hour or
> so, but I have one major caveat.  One of the
> accounting programs these offices use creates
> several temporary *.dbf files while they are working
> on it.  Using rsync without the --delete option
> would eventually leave hundreds of these files
> laying around.  However, if I do use the --delete
> option, those temp files may be deleted if a
> synchronization occurs while a user is still working
> with them. 
> 
> If there were a way to only delete files that were
> created BEFORE the last synchronization occured,
> then we would be in good shape, I think.  I haven't
> found any kind of option like that, though.
> 
> Any ideas? Advice? Other approaches?
> 
> Thanks -
> Stan
> 
> _______________________________________________
> http://www.ntlug.org/mailman/listinfo/discuss

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