Update to Murder docs (D69) and question on style.

[Michael Menge]

Hi,


Quoting Nic Bernstein <nic at onlight.com>:

> On 08/20/2015 09:07 PM, Bron Gondwana wrote:
>> On Fri, Aug 21, 2015, at 11:42, Nicola Nye wrote:
>>> On Fri, Aug 21, 2015, at 11:35 AM, Bron Gondwana wrote:
>>>> Murder plus replication is a giant ball of suck right now.  They  
>>>> don't know about each other, and they interact badly :(
>>> So is that a case for documenting "Here be dragons, enter at your  
>>> own risk" for the moment?
>>> Does it mean that admins should look at other backup mechanisms to  
>>> handle failover and redundancy in a murder environment, because  
>>> Cyrus's replication doesn't play nicely with murder?
>>> Or... ?
>> Or we need to fix murder and replication to work together nicely,  
>> but that's hard work[tm].
>>
>
> Ahem, some of us run Murderous Replicas all day long and it works  
> well enough...  Doesn't it? ;-)
>
> I can write this up, I just wasn't sure if it was still needed.  I  
> put a big ol' Note: in the replication page saying:
>
>    Important
>
>    Within a Cyrus /Murder/
>     
> <https://docs.cyrus.foundation/imap/developer/architecture.html#architecture-murder>
>    environment, replicas must *not* be configured to invoke
>    ctl_mboxlist(8)
>    <http://docs.cyrus.foundation/imap/admin/commands/ctl_mboxlist.html>
>    on startup (pushing the local mailbox list to the *Mupdate Master*).
>    This may only be done on the Master instance.
>
> That's the only real gotcha I know of, but, having said that, I did  
> write up a brief set of instructions about this very topic not that  
> long ago (IIRC) for user mailing list.  I figured I could start with  
> that.
>


For the initial configuration I second this. But there are IHMO things
to consider on failover.


1. ctl_mboxlist must be used with -m and -a Option on failover
2. on big installations updating all entries in mailbox.db on the
    mupdate server can take some time, on our setup we switch the IP address
    of master and replic on failover

Regards

    Michael





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