Coda File System

Re: data consistent

From: Steffen Neumann <sneumann_at_TechFak.Uni-Bielefeld.DE>
Date: 27 Jan 2003 10:49:31 +0100
Vojtech Moravek <vojtech.moravek_at_cz.tiscali.com> writes:

> [1  <text/plain>]
> thaks for reprly,
> 
> I mean case 2..
> 
> plese explain me simply,  how I use repair tool for solve the
> server-server problem..
[...]
> On Po, 2003-01-27 at 10:17, Steffen Neumann wrote:
> > or do you 2) *expect* them to be inconsistent simply because one 
> > was down for some time ?
[...]

I think you don't trust coda enough that it could handle this
situation itself, but I am pretty sure it does. (Jan, Ivan, 
please correct me if I get this wrong, I have no experience 
with multiple server installations. In case I got this right,
it could go into some manual or docs ?)


Things that work:

	Server1				Server2
	online				online

			Client1
		<---    modifies -------->
			file1
			
					Server2
					shutdown

			Client1
		<---    modifies 
			file2

					Server2
					back online

			Client1 
			accesses
			file2

	     -------->  automagic  -------->
			Server-Server 
			resolution 
			for file2


Things that don't work and need manual repair:

	Server1				Server2
	online				online

			Client1
		<---    modifies -------->
			file1

		NETWORK OUTAGE, server1 and server2 
		are separated, but BOTH ARE ONLINE.
		client1 talks to server1 
		client2 talks to server2

			    |
			    |
			    |
		Client1	    |	
	  <---  modifies    | 
		file2	    |
			    |
			    |	Client2
			    |   modifies --->
			    |	file2
			    |

		Network is back, but server1 
		has different modification of file2
		than server2 has. Conflict!

		Use repair tool to manually 
		diff the two versions of file2,
		choose between one of them 
		or merge (using favourite editor
		or other application) both modifications 
		into single file which then 
		goes to both servers.


So again, if one server is down, 
replication is automagic.
		
Yours,
Steffen

P.S.: Again set Reply-to: codalist









Received on 2003-01-27 04:51:39