Re: [Ltsp-discuss] NFS problem in old pentiums

[Francis A. <fr...@sh...>]

> Hello Again:-)
> I'm trying to put in work old pentium as clients. I have 100Mbits NICs
> (realtek8139 or 3C905C-TX-M) at the client's side but this configuration
> don't work. The client can't mount /opt/lts/i386, it says the server is
> not responding and can't get a request slot, but there is no problem if
> I use 10Mbps NICs.
> Searching on the web (and in the NFS-Howto), I found a possible
> solution: especify the rsize and the wsize, but normally it is put in
> the fstab. So, where can I put this values in the server?
> PD: Redhat7.3 on Server and kernel-2.4.18-ltsp
>
> Thanks,
>
> Luciano Andino

This is intriguing, because this is one of the very problems I had with
8139s running on my clients--many of which are quite old. I reported (on
this list, actually) that they were very flaky performers at 100Mbps, but
others reported no problems. My solution was to ramp down the cards to
10Mbps in the firmware, which worked fine.

One of the problems I had was clients repeatedly trying to get a request
slot on the pivot_root, even though server logs indicate that the client had
already recieved one. Sometimes it did work, though, but then the client
would function very slowly, and command-line parameters like ls would turn
up errors and garbage. Loading the 8139too module with higher verbosity
would report serving too many interrupts.

I have no idea how to change the nfs server's default r and wsize.  However,
to change the mount command line would mean digging into the boot image
ramdisk, changing line 206 of linuxrc (the mount command), and then
assembling a new image. I suppose you want to avoid this....

I still recommend simply ramping down the clients to 10Mbps in the firmware.
If your clients are that old that they can't support a weak chipset like the
8139 at 100Mbps, then they're probably too slow to be able to saturate a
10Mbps link in the first place (esp. if you're switched). Besides, you'll be
closer to the limit of the hardware with 100Mbps and an adjusted r and wsize
(if that actually works) than you would be with a 10Mpbs with the defaults.
Don't invite problems.
--
Francis Avila