On Tuesday, August 08, 2006 02:49:41 PM -0400 Derek Atkins
<[EMAIL PROTECTED]> wrote:
Ken Hornstein <[EMAIL PROTECTED]> writes:
I was specifically talking about DB servers. Having one of them go
down, provided there are no volumes on that server, should not cause a
problem, right?
In theory, no. In practice ... it's annoying.
The problem is that AFS clients pick a DB server to talk to at random,
and for most cases stick with that server. For a long-running bit of
software like the cache manager, a single server going down isn't a huge
problem; the client notices that server X is down, and then won't use
that server again. But for userland programs, they have no idea what
the current state is for ubik servers, so they pick one at random ...
and sometimes they pick the down one, and you get delays when using
"vos" or "pts". Those commands will eventually work ... they just
sometimes take a while to find the right DB servers.
I wonder if we could add a cache manager query so that apps could
ask the cache manager for server stats? Obviously this would be
an optional query, and the app should continue to use the current
random choice if there is no cache manager. But I think it would
help this case if there were some way to store this kind of state
on a client.
You mean like VIOCCKSERV, which tells you which servers the cache manager
currently thinks are down? Or more like VIOCGETSPREFS, which tells you
what preference order the cache manager has assigned to servers?
-- Jeff
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