[CentOS] RE: Keeping data on 2 servers in sync !

Wed Dec 7 19:34:58 UTC 2005
Denis Croombs <denis at croombs.org>

On 12/6/05, Jonathan Darton <jdarton at ibigroup.com> wrote:
>> >I want to build 2 servers (both running samba) to provide file 
>> >storage to 2 offices (approx 100 miles apart, linked via DSL) but all 
>> >data writen to 1 server must also be saved to the other server.
>> >Both servers would also allow users to access the data via a VPN thus 
>> >allowing 1 office with a failed server to access the other server via 
>> >the vpn and still see the data from both offices.
>> >I currently have 1 server working but we want to add the second 
>> >office to the system. (Currently 1 office has 10 users and the second 
>> >office has 1 user connected via VPN ) but the second office will have 
>> >20 within 12
>> months
>> >and the first will have 35 soon ))
>>
>> >Has anyone done anything like this ?
>>
>> I am currently synchronizing multiple office locations using a program 
>> called unison. Unison (http://www.cis.upenn.edu/~bcpierce/unison/) is 
>> a very well written program that can perform 2 way file 
>> synchronization. There are many configurable options with unison and I
recommend that you check it out.
>> In each office I have a PII350 128RAM Fedora or CentOS server running 
>> unison and the files are accessed via samba. I also configure samba to 
>> hide (veto) all of the temporary files used during synchronization. 
>> For redundancy I place a slave server with each master server that 
>> backs up all the user data / file system using rsync. This way if one 
>> of my $5 PII servers catches fire I can automatically switch over with no
downtime for the users.
>>
>> The only downfall I have encountered is with Autocad files not 
>> properly reading the synchronized .dwl lock file and more than one 
>> user working on the same file. As a work around for this I have 
>> configured Unison to keep a backup of the last 20 versions of a file. 
>> This way I can always hit my backups to retreive lost data. As a side 
>> note, if anyone knows a work around for the stubborn autocad dwl lock
file let me know :))!
>>
>> In any case my implementation has allowed me to synchronize file 
>> systems between 4 offices (3 in Canada, 1 in USA), using recycled 
>> hardware that was otherwise going to be donated/trashed.
>>
>> Let me know if you have any further questions.
>
>I'm about to do a Unison setup on two CentOS servers, so I'm thrilled to
see this response. I also work with Architects >>sometimes, so I'm
interested to hear about the dwl lock file issue.
>
>My one compound question: how are you invoking Unison? In batch mode, with
cron? How often? Wat other options did you 
>consider before settling on the scheme you use?

I see the project is no longer supported, do you have rpms for it ?

Thanks

Denis