Hello, I am seeking technical arguments for and/or against using a
direct (and not a indirect) automounter map to automount around 2000
/opt/ software packages. All our software is automounted as
/opt/${pkgname}_${pkgversion} (for now this setup cannot be easily
changed). Traditionally, this was done with an indirect automounter
map
auto_opt. When faced with the problem that a couple of packages in
/opt
needed to reside locally on the system itslef, two solution were found
by two different groups:

solution 1: continue to use an indirect automounter map for /opt, but
use lofs (loopback virtual file system) for those packages that need to
be installed locally on the system itself, e.g. by an entry in auto_opt
like this:

SUNWsan -rw,hard,intr ${HOST}:/var/opt/&

solution 2: change auto_opt into a direct map, so you can have
automounted entries in /opt as well as local directories in /opt

searching the we I found some arguments for/against indirect and/or
direct maps:

inirect map:

* reduces the number of NFS mount requests (1)
* reduces the size of /etc/mnttab
* changes are immediately available
* emulates a directory
* directory can not contain a mixture of "normal" mount points and
automount mount points (2)
* autoumounter mounts the top (parent) level directory subdirectories
are mounted only on request
* the automounter displays only currently-mounted file systems (3)

(1) not sure if this is still true for current autofs implementations
(2) lofs can be used to implement locally installed packages
(3) can be selected with recent autofs versions (nobrowse option)

direct map
* each entry is listed in /etc/mnttab
* each entry is an individual directory entry and treated as a separate
mount request
* automounter must be restarted to see changes
* directory can contain a mixture of normal mount points and automount
mount points

each entry of a direct map is added to /etc/mnttab and, AFAIK, needs to
be "watched" by the automounter separately. I am wondering if - based
on the kernel implementation - how bad is this imapct if you have
thousands of entries:

auto_opt as direct map: wc -l /etc/mnttab
1942 /etc/mnttab

auto_opt as indirect map: wc -l /etc/mnttab
64 /etc/mnttab

Any insides, thoughts, arguments about using direct vs indirct
automounter maps for /opt?

Cheers
--pwo
--
Peter W. Osel | pwo@Infineon.COM | pwo@pwo.de | http://pwo.de/
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