Re: Load average

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Author: Philip Hazel
Date:  
To: liaison
CC: exim-users
Subject: Re: Load average
On Wed, 2 Oct 1996, liaison wrote:

> I haven't been following this thread so please let me know if this issue has
> already been discussed...


I've only just started the thread!

> As I am in a "client <-> cluster <-> hub(s)" situation, what I really want to
> happen when the load average goes over a certain limit is for the smtp server
> to accept new mail from local clients (and queue it) but not accept mail from
> the hubs - and perhaps not even attempt to deliver mail it has queued, until
> the load is reduced.


It looks like the required feature is a list of escalating load average
thresholds to allow the following modes:

(1)  accept from anywhere (subject to the limits on numbers of SMTP 
     calls), and do immediate deliveries.


(2)  accept from some restricted list of hosts/networks and deliver 
     it; accept and queue mail from elsewhere.


(3) accept from anywhere, but just queue the mail.

(4)  accept only from restricted list, deliver it; do not accept from 
     elsewhere


(5)  accept only from restricted list, queue it; do not accept from
     elsewhere


(6) do not accept from anywhere

together with a separate threshold above which no deliveries at all are
ever attempted, i.e. queue runners don't do anything (7).

This looks like far too complicated a scheme to me. What does the list
think? How about having just states (1), (3), (5), and the (7) option?




--
Philip Hazel                   University Computing Service,
ph10@???             New Museums Site, Cambridge CB2 3QG,
P.Hazel@???          England.  Phone: +44 1223 334714