[OpenAFS-devel] fileserver problem

[Kuba Ober]

> > I do not know if OpenAFS nowadays has protection against clients with
> > one-way-connectivity using up all resources (threads or whatever) of
> > the server. The IBM versions don't seem to have such protection.
>
> I talked to the admin of the client and he told me that the machine
> is running WinNT and had installed two different versions of McAfee's
> VirusScan software. It was configured to scan all the network drives.
>
> So I think, there were two problems:
> - a newer version of VirusScan was installed without a deinstallation of
> the old version
> - the software was configured to scan all drives.
>
> Nevertheless should the server protect himself against a client
> using up all ressources of the server.
> I think there were a lot of scenarios where a client with an large AFS
> cache could simply read all the files he could reach.

Regardinbg one way connectivity: things can go mad, and that doesn't pertain 
only to AFS (NFS complains of not being able to allocate a slot, for example, 
which doesn't mean much at first glance), when somewhere on your switch or 
hub, there's a duplex disagree. We have a server connected to client machines 
via HP Procurve managed switch, and that switch, for whatever reason, 
sometimes switches the server's port to half-duplex mode. I had to disable 
autonegotiation and set kernel module options for the eepro100 card on the 
server to fixed full-duplex, 100mb/s, and set it same on the switch. All of 
our network cards are same eepro100 models. For some reason the switch would 
autonegotiate fine, and then after several hours, it would switch the port's 
mode to half duplex. As the network card was maintaining its fullduplex mode, 
most of the packets were getting lost, sometimes with either upstream or 
downstream part being affected more. It looked *very* strange and was a 
nightmare to debug. I was suspecting everything but our new switch...

Cheers,
Kuba