[OpenAFS-devel] Re: sanity check: client vldb cache time

[Andrew Deason]

On Wed, 22 Jan 2014 13:52:22 -0500
Jeffrey Altman <jaltman@your-file-system.com> wrote:

> When I refer to "2 hours" for the volume location information being
> cached it is an approximate upper bound on how long a client might
> continue using the data.   I am certainly not describing the inner
> complexities of the cache managers.

Neither am I; the Windows explanation earlier is simplified to the same
degree, but just pointing to specific parts in the code as I did so.

> The Windows cache manager will reset the volume location information for
> many reasons

Yes, I mentioned there are other conditions where the entry is reset;
they aren't relevant. (All of those cases cause the entry to be
potentially reset _more_ frequently than once per hour.)

> The one hour default lifetime for the daemon thread is an
> approximation because the deaemon thread does a lot of different jobs
> and some of them can block for extended periods of time.

Yes, it's an approximation. So, "approximately 1 hour" sounds like an
accurate description; certainly more accurate than "approximately 2
hours". If that background thread is delayed by an hour, that seems like
an extraordinary event; as far as I can tell, this is the same thread in
which we check for servers coming back up, for callback expirations, etc
etc.

-- 
Andrew Deason
adeason@sinenomine.net