[OpenAFS] Re: Performance issues

Jaap Winius jwinius@umrk.nl
Wed, 24 Aug 2011 05:03:20 +0200

Quoting Brandon Allbery <allbery.b@gmail.com>:

> First:  is the cache big enough?  The working set of even a lightweight
> desktop manager is pretty big.

It's currently set to 128 MB on all of the workstations. I could  
increase that, but by how much? I'm under the impression that, not far  
beyond this point, the returns tend to diminish.

> Second:  AFS is really designed for mostly read-only data.  Desktop
> environments are constantly updating the files in ~ so there will be a lot
> of writes.

I'm familiar with the description. But they put so much effort into  
supporting user volumes (client caches and all) that I guess I thought  
it might do better in this case than I had a right to expect.

> Third:  especially with Iceweasel/Firefox, you'll find that it helps a lot
> to symlink the cache into /var/tmp or other fast local storage. ...

Actually, each of our physical servers also runs a Squid proxy cache,  
so we decided to simply disable all of the browser caches.  
Nevertheless, when someone's user volume is remote, Iceweasel still  
runs too slow.

> ... (Desktop environments have caches as well, which again should be
> symlinked to local storage.) ...

Oh, that sounds like it will be worth a little extra performance!

> ... This still won't help with KDE/Gnome-like updating of application
> and system settings when you look at them funny, but it will help a lot.

When we were first setting up this system, we also tested the Gnome  
and KDE desktops just for fun. Gnome didn't do too badly with a remote  
user volume, but as I expected, KDE (my own favorite desktop) was just