Indirect mounts with map on automounted filesystem and --fstype=autofs

[Frank Thommen <fthommen@embl.de>]

Hi,

(I'm sure this has already been discussed on this list but somehow I 
seem unable to find the right thread or otherwise an answer on the web...)

I need to automount subdirectories of an automounted filesystem by using
an indirect map which lies itself on an automounted filesystem:

/base/sub1/        <- mounted via auto.master and indirect map
/base/sub1/sub2/a  <- mounted via indirect a map in /base/sub1

'sub2' is a "physically" existing directory in /base/sub1 
(server1:/export/sub1, in example below).


I managed to do it with the following:


/etc/auto.master
----------------
/base  file:/etc/auto.base --ghost


/etc/auto.base
--------------
sub1   /     server1:/export/sub1 \
        /sub2 -fstype=autofs file:/main/sub1/my.map


/base/sub1/my.map
----------------------
a   servera:/export/a
b   serverb:/export/b
...



My two questions are:

a) Is this the right and recommended way to use an indirect map which is 
located on an automounted filesystem or are the better/more 
efficient/faster ways to do it?

b) is the -fstype=autofs option an official option that will stay or 
rather an unofficial option that might disappear in the future?  The 
manpages don't mention this kind of filesystem 
(autofs-5.0.1-0.rc2.131.el5_4.1 on CentOS 5.4), so I'm unsure about it's 
status.


Thank you for any hint or referral to other online documentation.

    frank