[OpenAFS] Is OpenAFS for me?

Paul Blackburn mpb@est.ibm.com
Wed, 08 Mar 2006 14:50:38 +0000

Karl Bellve wrote:

> This is all new stuff to me...and very new "speak" as well...
> I don't think I meant volumes the way AFS means volumes, as you noticed.
> But, I would like to have a /afs/home that is 1TB made up of various 
> computers/drives. If I add a new HD to a new computer, can I now expand 
> /afs/home to include the size of the new HD, or must I make a new AFS?
> Going back to reread the AFS FAQ once more...

Hello Karl,

The neat thing about AFS is that you can manage the distributed
file space easily without disrupting users.

For example: if you want to add a new fileserver it's just
a matter of installing the OS, installing AFS, and configuring
it into your AFS cell.

You can then move AFS volumes from one of your existing fileservers
to the new one. This doesn't impact users actively accessing data.

This is very useful. You can empty an existing fileserver
(and fill a new fileserver) thus freeing up the old fileserver
for an operating system upgrade/reboot/whatever.

In my experience (AFS admin since 1993), it is useful to have
dedicated function AFS servers. For a highly-available configuration,
I would plan on having three dedicated AFS database servers
and (as many as you need) dedicated AFS fileservers.

The AFS database servers (running kaserver, ptserver, vlserver,
buserver) provide services to AFS clients (eg locating AFS file data).
I think AFS db servers are analogous to DNS nameservers.
They provide a data lookup service. So, db servers can be reasonably
lightweight machines.

Also note that you need to secure the kaserver(s)
(or kerberos5 server(s) from unauthorised login
because they hold the kerberos IDs and encrypted passwords.

AFS fileservers need to be fairly fast with large disk capacity.
It's fine to use hardware RAID to present big directory to the

Just a small point: "/afs/home" is unlikely.
The convention is that below the /afs/ directory the
local (and foreign) mountpoints are made.

So, you might have /afs/$your_cell_name/home/
although some sites use /afs/$your_cell_name/u/
(or even /afs/@cell/u/ :-)

Paul Blackburn
IBM Managed Security Services Delivery

PS: Good to know the FAQ is of some use. I know I have to update it. :-)
     It would be excellent to see the AFS Wiki restored.