[OpenAFS] Replication

Esther Filderman mizmoose@gmail.com
Thu, 26 Jun 2008 14:11:48 -0400

On Wed, Jun 25, 2008 at 7:07 AM, Lara Lloret Iglesias
<lari.lloret@googlemail.com> wrote:
> Hello,
> I've just installed two afs servers on the same cell, but I've problems with
> them. I've done a mkmount and everything works fine, but when I try to make
> another mount point, it just duplicates the content of the first one. I know
> afs has a replication system but I don't want to enable it, how can I turn
> it off??

The AFS replication system isn't as much about mount points as it is
the ability to make multiple read-only copies of a volume.

AFS replication allows you to say, "I want read-only copies of volume
foo.bar".  You (assuming you're an administrator) then use "vos
addsite" to tell the cell where to put the copies.  "vos release" then
creates the read-only copies of the volume, as foo.bar.readonly.

By default, AFS walks down the read-only tree.  Generally most cells
replicate critical top level volumes, such as root.cell, root.afs and
volumes that live under /afs/cellname/ .

To specifically access the read-write tree, you would specify
/afs/.cellname/{etc.}  Note the . before the cellname.

The advantage to read-only replication is that if the client loses
contact with one replica it will automatically switch to another.
This ensures uninterrupted access to data.

The disadvantages is that if all read-only copies are unavailable, it
will not switch to the read-write copy, and except for some tools
written by some of the geniuses here, there's no easy way to allow
non-AFS-admins the ability to release volumes, making the read-only
replication mechanism a poor choice for data that changes frequently.