The Pnfs Wormholes

Pnfs Wormholes are a kind of hardlink from each directory inside pnfs to one directory inside pnfs which doesn't need to be mounted. We are using this feature to influence the behaviour of HSM applications from one central point (directory) independently of the actual mountpoint the corresponding host has chosen. Wormholes are assigned 'per database' which means that the wormhole of directory trees of two different databases may point to different targets. (which is very unlikely to happen). There is a small set of things you have to prepare to make wormholes available.

Create the root of all config directories.
Get the pnfsID of that directory entry.
Create all necessary subdirectories of the root config directory you need. Only those directories can be accessed through the wormholes.
Assign the pnfsID of the wormhole target to all your databases using 'sclient'.
sclient getroot <shmkey> <databaseID> <pnfsID>
where <shmkey> is the shared memory key of your pnfs system as specified in /usr/etc/pnfsSetup, <databaseID> is the database identifier ( not the name ) of the database you want to assign to this wormhole and <pnfsID> is the pnfsID of the root config directory.
Now you may access all subdirectories of the config root via .(config)(<subdir>) whereever you are in pnfs.

What you need to know

There is no need to restart any of the deamons after setting or resetting the root config pointer with 'sclient'.
The wormhole will always point to the directory with the specified pnfsID. A rename won't change this fact because the pnfsID will stay with the directory whatever name it may have.
Removing the config root directory and creating a new one without redoing the procedure above will let the .(config) link point to void.
The actual configuration directories below the root config directory are referenced by name and not by pnfsID.
Whenever you create a new database you have to remember to get install the wormhole link. It won't be automatically done by 'mdb create ...'.

Example

#
# create the config root
#
mkdir -p /pnfs/fs/admin/etc/configdir
#
# get the pfnsID of configdir
#
pnfsID=`cat /pnfs/fs/admin/etc/.(id)(configdir)`
#
#  create the actual configuration directories below configdir
#
mkdir /pnfs/fs/admin/etc/configdir/tools
mkdir /pnfs/fs/admin/etc/configdir/flags
#
# asign the config directory to the databases.
# lets say we have 4 databases 0...3
# and our $shmkey is 1122 
#
for c in 0 1 2 3 ; do
  $pnfs/tools/sclient getroot 1122 $c $pnfsID
done
#
# from now on 
# .(config)(tools) will point to /pnfs/fs/admin/etc/configdir/tools  and
# .(config)(flags) will point to /pnfs/fs/admin/etc/configdir/flags
#
#    ask the database for the installed wormhole link
#    ( just omit the last argument )
#
for c in 0 1 2 3 ; do
  $pnfs/tools/sclient getroot 1122 $c
done
#
#  you will learn the database id, the root id of that database and
#  wormhole link (pnfsID)
#