odd problem with distributed erlang system

Miguel Barreiro Paz <>
Mon Mar 31 14:32:12 CEST 2003

> It was on Debian 3.0 (Linux 2.4.18 kernel) with OTP R9B and an
> automounted NFS volume. I had lots of problems to make the automounter
> use the mount options I wanted, partly because the automounter I used
> (amd) seems to not use the mount command, but a library API, so when I
> was done I had changed automounters, written some weird scripts, etc.

NFS on Linux has traditionally been a weak spot. It's much much better
today. My experience on nfs on linux:

- dump amd and use autofs instead
- force rsize and wsize to 8192 if autofs doesn't do it for you
- use NFSv3 (yes, it's marked "experimental", but has been in use here for
a _long_ time without worry. Maybe we just were lucky)
- mount "hard" or "hard,intr"
- NFSv3 over TCP is still a little bit unreliable in my humble experience.
- Async mounts are perfectly OK in a LAN for most purposes.
- use jumbo frames if you're on 1000Base-* and hardware allows (1 ether
frame per 8KB NFS datagram is nice)
- tcpdump is your friend, as you already know :-)

> The solution was to not mount the volume synchronously, i.e I added the
> mount options: "async,actimeou=0". The "actimeout=0" flag sets attribute
> caching timeout to 0, which is pretty syncronous, and will do for me.

Not quite the same as "sync" but good enough unless someone runs a mail
spool or something similarly insane on that fs.

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