Yan Fitterer wrote:
>>> In the attached pe- warn, why is resource R_audit being started
>>> on idm01 when there is an INFINITY constraint with uname eq
>>> idm04?
>>>
>>> BTW - idm04 is in standby at the moment. That should hardly
>>> matter. I expect the resource to be "cannot run anywhere".
>>>
>>> I really hope it's not a typo, but I have read it as much as I
>>> can, and I can't see it...
>>>
>>> Thanks Yan
>> So, there is only one place it can be run, and it has score 0. (It
>> can't run on a machine in standby).
>>
>> So, it gets run there.
>>
>> What's the problem?
>
> The problem is that I need the resource to _ONLY_ run on IDM04, or
> not at all. Yes, I know, this is not clustering, or HA, but there is
> a good reason.
>
> If you want the long story, the reason for that is that resource
> R_audit (an instance of Novell Audit) is not meant to be clustered
> here, but depends on resource R_workforce_edir (eDirectory instance),
> which IS clustered. The issue is that Novell Audit must start after
> eDirectory (Audit configuration is stored in eDir). So the best way I
> could think of achieving that, was to created a resource for Audit,
> with an order constraint between eDirectory and Audit. But since
> Audit isn't really clustered (executables on one node only), I need
> to make it run on IDM04, or nowhere. That what I thought INFINITY
> would mean.
>
> If -INFINITY achieves that, but INFINITY doesn't, then it looks like
> broken logic to me, where INFINITY is not the exact opposite of
> -INFINITY. If this is really "works as designed", it is very highly
> counter-intuitive, and IMHO should be considered a bug.
>
> Actually, INFINITY in colocation constraints _does_ mean, "work here
> or nowhere". Why would it be different for location constraints?
Well, that's a good question. One that Andrew and I have discussed a
few times when I've asked him with replies including phrases like "you
don't know how the code works" and what seemed like a certain amount of
tension in the discussion.
You see, I have the opposite impression of yours. I think it's the
colocation logic that's backwards ;-).
But regardless, it's clear that the logic is not consistent.
For resource location, a resource can be located anywhere that has a
positive score.
For colocation, I'm not sure if a net negative score prohibits
colocation or not...
If you search the mailing lists, you'll see that I have recently
recommended that we avoid recommending using +INFINITY for location
constraints, because it swamps all other constraints -- unless you know
that only exactly one node will have +INFINITY.
I just added your question to the CIB Idioms page:
http://linux-ha.org/CIB/Idioms/LocationOnlyOnCertainNodes
http://linux-ha.org/CIB/Idioms
--
Alan Robertson <[EMAIL PROTECTED]>
"Openness is the foundation and preservative of friendship... Let me
claim from you at all times your undisguised opinions." - William
Wilberforce
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