Re: [Moosefs-users] changelogs on the metalogger

[Bán M. <ba...@vo...>]

On Mon, 6 Sep 2010 16:17:08 +0200
Bán Miklós <ba...@vo...> wrote:

> Second problem:
> If I stop, wait and start the metalogger server, the changelog will be
> inconsistent. The changes from the master server, while the metalogger
> was being stopped, not arriving after I turn it back on. 
> Is there any recommendation how can I manage the metalogger servers
> to keep coherent change logs after failure situation?

Hi,

I wrote two initiation script. One start the mfsmaster and the other
the mfsmetalogger. It is a tcp based client server socket pair. If I
restart a metalogger server it is sending the last changelog line to the
masterserver. If that line differ from the masters's last changelog
line the masterserver restarting and send back the new metadata.mfs to
metalogger server. The metalogger server after receiving a new metadata
file clear the changelogs and restarting or starting.

It works and I think it is not a wrong way, but there is a problem:

If there is a file operations while I restart the masterserver, what
happening? 
Is there a lock mechanism on the filesystem while the mfsmaster is
restarting?

more..
I think there is no this client-server process to manage this
kind of metadata updating, because it is possible to implement into
the main code. Opinion? It is too difficult for me. Sorry.

Would it be interesting to send these two script to the maillist?

&Miklos