On Mon, 11 Apr 2011, Ian Kent wrote:
On Thu, 2011-04-07 at 15:29 -0600, Michael Coffman wrote:On Thu, Apr 7, 2011 at 8:56 AM, Ian Kent <ra...@themaw.net> wrote: On Wed, 2011-04-06 at 12:52 -0600, Michael Coffman wrote: > Hello, > > I am trying to use the -host map for global access to servers in my > environment. > > I have noted on this list that after the first mount of a server via > host mapping, the server is never again probed for mount points. This > seems like a major flaw in the host map functionality. This is a > problem when adding new file systems to our NFS servers. It means > systems have to be completely idled in order to get them to unmount > and re-mount the servers to see the new mount points (not possible > very often in my environment). > > Is the assumption that if you use host mapping, your server will > either never change, or you have the ability to 'reboot' your > environment when a new file system is added to a server?Neither. The problem is that exports can be nested and frequently are (think of the nohide export option). For example, with exports like: /export/vol1/data1 /export/vol1/data2 and then add: /export/vol1 and update the map when either or both /export/vol1/data1 and /export/vol1/data2 are mounted, /export/vol1 is accessed it will cover these mounts. Now that might not seem like a problem but when you end up with multiple layers of mounts mounted multiple times everything starts to get confused really fast. First off, thanks for the reply and the details on the reasoning for not automatically re-scanning servers that have been mounted via host mapping. I guess in my simple world I would never export a higher level directory if sub-directories were already exported. Do lots or people really nest exports to the same sets of client systems? I will have to think about some scenarios and some possibilities of algorithms on how to deal with them and get back with you... In any case, it seems having a way to ping autofs and have it re-read would imply that the admin would have some knowledge of what was being requested. > > Is there any way that functionality could be added that would allow > for sending a signal ( say USR2 ) that would cause the automounter to > re-run /etc/auto.net to re-query -host managed servers for new file > systems? Well, if you have sensible, realistic, workable ideas on how to handle the nesting problem then share. And I don't mean "just do this ...." type through away comments that have no workable basis in fact. Hopefully this will not come across as me saying 'just do it' :) We have used AMD for years and I would really like to switch to autofs and was planning on doing so until this issue came up. I believe that some kind of knob that could be used to refresh the maps on my clients so they see new exports when added to the servers would be very useful. Not an automatic re-querying of the servers, but a signal that I can bump automount with when I know what changes have been made on the other end and want to refresh.I'll think more about it. Perhaps, if I can work out some way to check for active mount within nested set of exports, I could ignore the nested ones on update. The problem then will be people complaining that "suddenly it stopped seeing new mounts when I added them".
Thanks for being willing to at least think about it...
Thanks again for taking the time to reply to my message. Ian -- -MichaelC
-- -MichaelC _______________________________________________ autofs mailing list autofs@linux.kernel.org http://linux.kernel.org/mailman/listinfo/autofs
