Coda File System

volume names

From: Ivan Popov <pin_at_math.chalmers.se>
Date: Mon, 2 Jun 2003 13:47:07 +0200 (MET DST)
Hello,

as the long awaited cell (realm) aware Coda has come,
many of us will remake the setups, adjust them to the new paths,
possibly recreate volumes...

That's why I am repeating below the points already mentioned on the list
by myself and others.

I feel it is *now* we (you!) have the chance to change the volume name
assignment discipline.

Nowadays Coda has provisions for one-to-one mapping of paths and volume
names. Moreover, it is the default for "cfs mkm" - thanks Jan!

That is, if you just do

cfs mkm /coda/realm/directory/mydata

it creates the corresponding mountpoint for a volume called

"/directory/mydata"

And of course, a logical choice for the root volume name is then

"/"

It that way you do not have to make *two* choices for placing a peace of
data:
 - its volume name
 - its mount point
you choose just a common *one*.

Neither have you to bother about where does that volume "testdata"
found by "volutil getvolumelist" belong?...

The suggestion is based on experience with DFS where we even had to
develop a special tool for mapping paths to volume names and back (due to
the incompatible character sets), to make it manageable.

You do not loose anything by beginning with the discipline as above, but
you'll be glad you did, later on, when you face hundreds or thousands
of volumes, devoted to dozens of different purposes (not only users, and
mail, and software, and ... and ... but also departmental projects, and
general ones, and private ones, and temporary things and ... and ... and
... :)
and possibly facing also multiple fellow volume administrators and having
to agree on name assignment policies :-)

The only "but" is still the volume name limitation of 32 characters,
thus limiting the depth of mountpoint placement in the Coda tree.
I hope it will be lifted as time goes, otherwise the old style mounts are
still around, and a last resort alternative.

For over a year I have run Coda servers and clients not implementing
Get Root Volume Name RPC at all - and never had any problems because of
that, all my root volumes, in several cells, are just "/".
I suggest proclaiming other root volume names deprecated, so that the
named RPC could be eventually phased out, thus encouraging the
straightforward naming policy.
There is literally no reason for having an arbitrary root volume name.
Neither any good reason for keeping with not-path-conformant ones.

My 2c^H^H$2 :-)
--
Ivan
Received on 2003-06-02 07:48:57