[OpenAFS] Disconnected OpenAFS

Zach netrek@gmail.com
Tue, 25 Sep 2007 03:36:08 -0400

Could we have a disconnected mode for say just a user's $HOME
directory. It's likely files in there won't change while they are
offline. I run openafs client on my laptop and I use intermittent
dialup internet access. It takes a long time to do an operation such
as ls for the first time but then it's cached and is much faster, but
the cache doesn't seem to last very long (around an hour or so).
Anyway to optimize this offline mode for low bandwidth users in terms
of reducing update size and lowering the time to do caching?


On 9/25/07, Jeffrey Altman <jaltman@secure-endpoints.com> wrote:
> Jim Rees wrote:
> > Jeffrey Altman wrote:
> >
> >   You do not need to have all of the callbacks at once.  You can perform
> >   your check and mark files/directories disconnected a bit at a time.
> >
> > I don't understand that.  If you don't snapshot the state of your file
> > system at one particular instant, won't you have an inconsistent view of the
> > file system?  What do you mean by "mark files/directories disconnected?"
> For each vnode in the cache, you keep track of the
> connected/disconnected state.  While you are in the transition from
> connected -> disconnected you sync files into the cache and mark them
> disconnected.  When a request comes in for a file marked disconnected,
> you treat it as if disconnected mode was active.
> For disconnected -> connected transitions you do the same in reverse.
> You sync the files back to the file server and then remove the
> disconnected flag.  Files/directories that are in a conflict state
> remain disconnected until the end user deals with the conflict and
> decides what should be done.
> We can't give a user a perfectly consistent view of the entire afs file
> system space.  What we can do is provide a mostly consistent view of the
> portions of the file system space that the user cares about.  Note that
> a user can only care about as many files as fit in the cache.
> Jeffrey Altman
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