[ClusterLabs] Antw: [EXT] Re: Order constraint with a timeout?

[Ulrich Windl]

>>> Ken Gaillot <kgaillot at redhat.com> schrieb am 29.03.2022 um 01:25 in
Nachricht
<864c5d56cb507b2964c72ae0e38eb0c2459ebb2e.camel at redhat.com>:
> On Mon, 2022‑03‑28 at 17:26 ‑0400, john tillman wrote:
>> > On Mon, 2022‑03‑28 at 14:03 ‑0400, john tillman wrote:
>> > > Greetings all,
>> > > 
>> > > Is it possible to have an order constraint with a timeout?  I
>> > > can't
>> > > find
>> > > one but perhaps I am using the wrong keywords in google.
>> > > 
>> > > I have several Filesystem resource and one nfs service
>> > > resource.  If
>> > > I
>> > > create 3 order constraints:
>> > >    pcs constraint order start fsRsc1 then start myNfsServiceRsc
>> > >    pcs constraint order start fsRsc2 then start myNfsServiceRsc
>> > >    pcs constraint order start fsRsc3 then start myNfsServiceRsc
>> > > 
>> > > I would like to make sure that the nfs service will be started
>> > > even
>> > > if one
>> > > of the Filesystem resources fails to start.  Is there a timeout
>> > > that
>> > > could
>> > > be used?
>> > > 
>> > > There is the "kind=Optional" parameter but that looks like it
>> > > will
>> > > immediately start the second resource if the first failed to
>> > > start.  There
>> > > is no timeout option.
>> > > 
>> > > Best regards,
>> > > ‑John
>> > > 
>> > 
>> > How do you envision the timeout working?
>> > 
>> > You can add a timeout for the ordering itself using rules, where
>> > the
>> > ordering no longer applies after a certain date/time, but it
>> > doesn't
>> > sound like that's what you want.
>> > ‑‑
>> > Ken Gaillot <kgaillot at redhat.com>
>> > 
>> 
>> Thank you for the reply, Ken.
>> 
>> I was hoping that I could give the Filesystem resource "X" seconds to
>> start.  If it failed to start after "X" then I would start the nfs
>> service
>> anyway.  So Those Filesystems that successfully started could be
>> accessed,
>> albeit with a bit of a delay before nfs is started.
>> 
>> Basically, I want to start the nfs service regardless of whether any
>> or
>> all of the Filesystem resources started.  But I want to give them all
>> a
>> chance start before starting nfs.
>> 
>> That said, it doesn't look like the rules suggestion you made is what
>> I
>> need.  Any other ideas?
>> 
>> Best Regards,
>> ‑John
>> 
> 
> I don't think there is a way to do that except maybe with customizing
> the filesystem resource agent.

Hi!

I'm not sure, but isn't there a mechanism like "start a set of resources
first, then start another one".
What is probably wanted is to ignore the failure of some of those set
members.
So I wonder: What use is HA if the guarantee is "the filesystem might be
there"?
Still: what about on-fail=ignore (for start) for those filesystems that aren't
considered essential?

Regards,
Ulrich


> 
> If you customized the agent, you could have it set a transient node
> attribute (like fs‑<RESOURCE ID>) when attempting to start, regardless
> of whether it succeeded or failed. Then you could configure a location
> constraint for the nfs server using a rule that allows the nfs server
> to run only on a node where all three node attributes have been
> defined.
> ‑‑ 
> Ken Gaillot <kgaillot at redhat.com>
> 
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