SUMMARY: yserv cache problem, etc?

From: sys013@aberdeen.ac.uk
Date: Fri Jul 14 1995 - 11:16:56 CDT


I don't seem to have a fix for this problem, but got some hints. Perhaps
there's no fix!

Suggestions (for clearing info cached by ypserv) were:

        1. try ypwhich -m from the client.

I didn't get any mileage out of that.

        2. go back to using ypxfr/yppush

If I have to!

Other handy-hints were:

        1. Make sure you don't yppush to slaves which are a.w.o.l. eg
          try ping/rup or rpcinfo first.

        2. Use -ypsetme when starting ypbind to simplify things.

        3. Use rpcinfo to de-register a ypserv which is not behaving,
           rather than trying to restart it.

        4. Try The NYS version of ypserv.
This isn't quite ripe yet, judging by the documentation, but looks good for
the future (NB I didn't try it out).

        5. The place to put a 'ypservers' file is
          /var/yp/binding/DOMAINNAME/ypservers
But "-ypsetme" is favoured for getting bound to oneself.

It seems from the replies I've had, that the workings of ypserv are mostly
mysterious!

Thanks to:

dmh@mozart.att.com (Dave Hughes)
jram@morgan.com (J. Rambhaskar)
"David Evans" <djve@deakin.edu.au>
Dan Stromberg - OAC-DCS <strombrg@hydra.acs.uci.edu>

The original query:
Folks,

I've been trying to reduce the load on our network and NIS (YP) master server,
imposed by pushing NIS maps . We have a large number of slave servers, and some
VERY large maps. During the frenetic registration of students at the start of
last session, we had some terrible problems, which I'd like to avoid this
year. What I've tried to do is to periodically propagate increments w.r.t a
set of reference maps, using rdist, and then re-make the maps on the slave
servers. The reference maps are set up on the slaves just after midnight.

It all works - up to a point. The problems arise because of (what I presume to
be) cacheing within ypserv, ie a specific server has an OK map (makedbm -u),
but serves up old data on a lookup. After a while it serves up the new data. "a
while" can be up to 35mins.

I've tried HUP-ing ypserv to no apparent good. I've also tried restarting
ypserv, which works, but makes me nervous. It often takes ages, which I
presume to be related to binding overheads. I'm aiming for a 5-minute update
cycle. I notice that ypxfr has some way of nudging ypserv so that it clears
it's cache (for just the subject map?), so I wonder if there's some way I can
do the same?

BTW, I'd quite like my slaves to bind to themselves: does anyone know of a way
to do this (other than ypsetme)? The NISKit for Solaris2 docs hint at a
"ypservers" file, but I cant find any info on this for SunOS (4.1.3_U1).
Perhaps there's a way of building an appropriate binding file?

ALSO: Why do I find strange names in my yp/binding directory - ie names not
related to my one-and-only NIS domain, but suggestive of other NIS domains
on our LAN?

Thanks in anticipation,

Gordon

-------------------------------------------------------------------------
Gordon Robertson, Head of Systems, Aberdeen University Computing Centre
Tel +44(0)224 273340
E-Mail : g.robertson@abdn.ac.uk
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