Red Hat Bugzilla – Bug 139417
[autofs] replicated host choice algorithm ignores weights in favor of local mounts
Last modified: 2007-11-30 17:07:05 EST
Description of problem:
autofs always chooses a local entry, if present. This is fine in the general
case, but not when weights have been explicitly assigned to the hosts such that
localhost only be chosen as a last resort.
Steps to Reproduce:
1. Set up a replicated entry in /etc/auto.misc (eg: 'rep
host1(1):/exports/e1,localhost(10):/exports/e2) and restart autofs
2. ls /misc/rep
3. cat /proc/mounts | grep nfs
The localhost mount was chosen in spite of it's higher weight.
host1's export should have been mounted since it was given the lower weight.
See /usr/share/doc/autofs-4.1.3/README.replicated-server for explanation of
It is our goal to maintain compatibility with the Sun automounter, so
that it will integrate seemlessly in mixed environments. To that end,
please refer to the Sun documentation for the desired behaviour, and
report bugs on devaiations there from.
In this particular instance, the following paragraph from the Sun
automount(1M) man page apply:
Server proximity takes priority in the selection process. In the
example above, if the server delta is on the same network segment as
the client, but the others are on different network segments, then
delta will be selected; the weighting value is ignored. The
weighting has effect only when selecting between servers with the
same network proximity.
I'm a little puzzled by what the client is doing, here. Why would you
want to fall back to a local mount? In the Sun implementation,
replicated server functionality is only available if the mounts are
read-only. In that case, why wouldn't you prefer to read the local copy?
The customer would like to be able to specify to use a local mount point last
when he has replicated servers for automount. In his case he will back up his
NFS exports locally at regular intervals, but they will be out of date since
they only sync occasionally to the nfs servers. He would only like to use this
local backup only if the two other servers become unavailable.
Unfortunately this is the expected (but not quite documented) behavior
in the linux automounter. I have updated the documentation to reflect
its behavior. (We try to provide compatability as much as possible
with the Sun automounter, and it behaves this way as well).
The documentation has been updated in autofs-4.1.3-81.