From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Fri, 18 Dec 1998 21:34:08 +0100
From: Bengt Kleberg bengt.kleberg@swip.net
Subject: [9fans] Keeping a Plan9 domain's time consistent
Topicbox-Message-UUID: 8d49fbc0-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19981218203408.Ew-qJx8UGrMmdfMD98Z_Lu5-2JJlBHizcC5_NXp9W4A@z>

In article <199812181728.LAA22026@ns.dbSystems.com>, 9fans@cse.psu.edu wrote:

> Hello 9fans!
> 
> I've started thinking about how to keep time consistent
> in a Plan9 system.  This is one problem that is common
> with most distributed systems.

My favorite books on the subject (distributed systems) always suggest that
one should avoid a centralised solution. This is due to the lack of
scalability of such a solution. However, with a Plan9 system the auth
server is a centralised already, no?

> We could use timed between the file servers and increase
> the frequency of the cpu/terminal systems syncing their
> time using the existing stat of /.  This would keep the
> overhead of the timed protocol down.

(I will try to understand this and perhaps comment if I manage)

> Or we could run ntp on the auth server and slave all the
> other systems from that.

How about mount:ing /dev/time from the auth server? Would that save the
other systems from running ntp?
 
> The only requirement is that the protocol be il or udp
> based so we don't have to add tcp to the file servers.
> 
> Any thoughts?
> 

Would a DNS like system make sense? File servers sync with the auth
server. Cpu servers sync with a file server (the least recently used).
Terminals sync with cpu servers (also the least recently used). I hope
this is a none centralised suggestion, and that it might scale.