[CentOS] Implementing LVS changes made in Piranha GUI

Thu Sep 25 21:43:37 UTC 2008
Barry Brimer <lists at brimer.org>

Quoting David Dyer-Bennet <dd-b at dd-b.net>:

> On Thu, September 25, 2008 14:43, Barry Brimer wrote:
> > Quoting David Dyer-Bennet <dd-b at dd-b.net>:
> >
> >>
> >> On Thu, September 25, 2008 14:13, Barry Brimer wrote:
> >>
> >> > Is the service itself active?
> >> >
> >> > Do you have a line above these that says something like:
> >> >
> >> > virtual example.com {
> >> >      active = 1
> >>
> >> Yes; and it shows as active in Piranha, too, and nannys got started for
> >> the three real servers.  It just didn't tell ipvs to actually route to
> >> them.
> >
> > What happens when you run the service check by hand?
> Don't know what "service check" means (guessing you mean what nanny does
> to decide a service is working?).  But raising the issue of whether
> something below the level of what I thought I had changed was changed has
> been somewhat productive.
> While I can ping the realservers, turns out I can't access the services on
> them.  Don't know why yet, but that's something I can investigate.  (Still
> don't see why it changed when it did; but if I can't access the services
> from the lvs, then it can't route to them either, and the nanny checks
> will fail, etc., so that must be fixed before anything can work.)  I will
> chase this down, and either fix it or have different questions :-).  Thank
> you!
> > Do you have your IP addresses for different services on different devices
> Yes, they're on separate devices, and they're set up the same was as when
> it worked yesterday, so I don't think it's anything that basic that's
> wrong.
> I think I've been mis-understanding the startup order.  Is this what
> really happens:
> 1. pulse started
> 2. lvsd started by pulse
> 3. nanny for each (active) realserver started by lvsd
> 4. When a nanny gets a successful test, either it or lvsd *then* enables
> that realserver for receiving traffic
> That would explain why I have nannys running, but no realservers listed by
> ipvsadm.  I expected things to start out on, and only get turned off if
> the nannys failed; but in fact doing what I listed above makes more sense,
> it's better if you *have* a nanny to make sure the nanny reports ok
> *first*.

By service check, I mean the send or send program line which "expects" the
result of the "expect" line to determine that the service is "up".

IME, ipvsadm does not show a host (even at startup) until it is successful from
the send/send program / expect tests.