[OpenAFS] openafs 1.8.7 clients and server 1.6.24: rx ping burst?

[Giovanni Bracco]

Recently we have upgraded many of our clients to OpenAFS 1.8.7 while 
fileservers run 1.6.24.

We have noticed some delays for client in accessing the root.cell volume 
through the path /afs/.enea.it so we have moved root.cell to a new 
server where it is the only volume and we have done some tcpdump to 
understand.

First of all the access to root.cell should be rather rare, as normally 
the path is /afs/enea.it and the volume is replicated on 5 fileservers 
in different sites. So  the frequency of access to this volume is a bit 
strange, but it may be that some software has been installed on the RW 
path and so we are looking to this problem.

But the real strange thing is that there are  1.8.7 clients that are 
sending hundreds of rx ping to this server in less that 30s, messages 
like this:

15:50:37.414106 IP cresco4cx021.casaccia.enea.it.afs3-callback > 
linafs3.frascati.enea.it.afs3-fileserver:  rx version (29)

384 similar lines up to:

15:51:17.494530 IP cresco4cx021.casaccia.enea.it.afs3-callback > 
linafs3.frascati.enea.it.afs3-fileserver:  rx version (29)

I do remember a problem of this type when 1.6.x clients where introduced 
(2011..) but are there reasons for this problem to emerge again for the 
combination of 1.8.7 clients and 1.6.24 fileservers?

Clients which openafs 1.6.24 do not show the same problem and in a 
tcpdump time monitoring of 60 seconds make 3 rx ping, not hundreds!

This corresponds to 20 s ping period time that seems to be what expected
For example in the thread
  https://lists.openafs.org/pipermail/openafs-info/2011-December/037193.html

Any comment or suggestions?

Are 1.8.7 clients compatible with 1.6.24 servers? Have we  missed 
something in the documentation?

Giovanni


-- 
Giovanni Bracco
phone  +39 351 8804788
E-mail  giovanni.bracco@enea.it
WWW http://www.afs.enea.it/bracco


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