Coda File System

Re: resolution is turned off

From: Jan Harkes <jaharkes_at_cs.cmu.edu>
Date: Fri, 14 Dec 2001 12:07:59 -0500
On Fri, Dec 14, 2001 at 11:02:34AM -0500, Tom Carroll wrote:
> A coda 5.3.17 (FreeBSD 4.4-Stable) server repeatly reports the following:
> 
> Caution, replicated volume 0x10000002, resolution is turned off
> 
> The message is reported when a moderate (~250MB) amount of files are
> initially loaded onto a volume.

Servers themselves don't really know whether the volume they are hosting
is part of a replicated group or not. As soon as a volume has multiple
replicas we merge server logs during the resolution phase.

These logs are normally truncated by either resolution, or by the COP2
messages (commit operation phase 2 or something). With replicated
volumes, if the COP2 is lost, there will be a discrepancy between the
servers which triggers resolution. This doesn't happen on replicated
volumes with only a single replica, so the logs can grow unbounded by
lost COP2's and at some point the server runs out of available entries.

Some attempts were made to 'dynamically' figure out whether we were a
single replica or not and to avoid logging, however some things still
leaked through. In 5.3.17 we now completely disable logging at the time
we create a replicated volume with ony one replica. It should actually
have worked before, but there was a stupid mistake in the createvol_rep
script.

So these messages are harmless on singly replicated volumes, they should
result from the few cases where we used to leak a resolution log entry.

Jan
Received on 2001-12-14 12:08:05