Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!kane
From: kane@svax.cs.cornell.edu (Kenneth Kane)
Newsgroups: comp.sys.isis
Subject: Re: ISIS logger question
Message-ID: <32798@cornell.UUCP>
Date: 3 Oct 89 16:03:25 GMT
References: 
Sender: nobody@cornell.UUCP
Reply-To: kane@svax.cs.cornell.edu (Kenneth Kane)
Organization: Cornell Univ. CS Dept, Ithaca NY
Lines: 24

The log manager currently checkpoints the state of a group member when that
member's log contains either 250 messages or 1 megabyte total.  These
numbers were chosen based on the typical traffic and message size we saw
in ISIS at the time the log manager was developed.  I should also point
out that a checkpoint is taken at a group member at the time the member
joins the group.  As a result, the logs of different servers may contains
different checkpoints as well as different logged messages; and therefore
future checkpoints may be taken at different times at the group members.

There has been some discussion about making these parameters adjustable
to the application.  However, I have been busy lately writing my thesis
and job hunting, so I haven't had a chance to implement this feature.
There has also been some discussion of allowing an application to force
checkpoints of group states.  The problem with forced checkpoints is
that they can create synchronization errors within the log manager.
We'll have to take a closer look at this, though, to determine if it
is at all feasible.

The question of when the log manager choses to checkpoint has been brought
up by several people recently.  We will be sure to include a discussion in
the next version of the ISIS manual.

Ken Kane
kane@svax.cs.cornell.edu