[Linux-ha-dev] Re: [Linux-ha-cvs] Linux-HA CVS: membership bygshi
Andrew Beekhof (GMail)
beekhof at gmail.com
Wed Feb 16 00:11:38 MST 2005
On Feb 15, 2005, at 8:05 PM, Alan Robertson wrote:
> Andrew Beekhof (GMail) wrote:
>> On Feb 15, 2005, at 7:21 PM, Alan Robertson wrote:
>>> Andrew Beekhof (GMail) wrote:
>>>>> Not at all true.
>>>>> I see the confusion.
>>>>> What I meant was crash the machine locally -- without using
>>>>> STONITH. This is easy, and it's *like* STONITH - but doesn't use
>>>>> the OfficialSTONITHCode(tm).
>>>> Oh thats so evil. Why would we prefer this of calling STONITH? I
>>>> mean we're going to have to anyway since the node is now unclean
>>>> (left without permission)
>>> Crashing is crashing. This is a built-in, documented API for
>>> crashing on machines which maintain basic communications sanity.
>>> Evil seems a little strong an adjective, IMHO... ;-)
>>> It will ALWAYS work - even when STONITH isn't configured, or the
>>> STONITH hardware is flaky - and it's probably faster than STONITH.
>>> I'm having trouble following all the levels of message nesting
>>> above, and which questions you were asking me to respond to. So,
>>> I'll start over...
>>> Right now, you don't pay attention to quorum at all.
>>> For a 2-node cluster - you can do as you please - and you needn't
>>> have quorum. OR you can require it. I would see this as an option.
>>> For quorum we can add a ping-node-vote option to the membership
>>> The "best" way is to enable both options - at least for 2-node
>>> But, it's not so obvious that both should always be enabled in all
>>> Some would claim that quorum shouldn't be declared without fencing -
>>> but that's a separate subject.
>> Missed a couple, so I'll re-ask :)
>> You pointed out the loss of consciousness situation:
>>>> If you cannot contact any node when you first come up, then EVERY
>>>> node you cannot contact must be STONITHed. ("everybody must get
>>>> stoned" - as Dylan might say). No doubt some delay would be in
>>>> order for this case.
>> Then I said:
>>> I believe that if we amend #2 above to also include nodes it has
>>> never seen (code for this is in CVS) _and_ amend the CIB startup to
>>> erase the status section after reading the config from disk (so that
>>> we're saying _no_ nodes have been seen)... then we have the bases
>>> covered right?
>> Would you agree? or am i still missing a case?
> I believe that's right. I'd have to know more about your code to know
> for absolute certain - but it certainly sounds right to me. [I didn't
> answer this one because we'd talked about it on IRC and/or the phone,
> and I agreed ;-)].
Well the code is of course perfect :)
I just thought I'd make sure I hadnt forgotten anything we discussed.
>> The other part was that you appeared to be saying that:
>> - we cant allocate resources until we shoot the unknowns, and
>> - we cant/shouldnt shoot the unknowns until we have quorum
>> To me it follows that the cluster cant do resource management until
>> we have quorum.
>> So my question was: Is that what you meant and if so, is that really
>> we want?
> I think I answered this. But, perhaps it wasn't completely clear, or
> perhaps I didn't answer the question...
> >> For a 2-node cluster - you can do as you please - and you needn't
> >> quorum. OR you can require it. I would see this as an option.
> The "option" part isn't for 2-node only - at least not in my mind...
> It might be a good default all the time to have it on, but if you have
> the option, then I'd still have it available in all configurations.
> Is this clearer? [or did I miss the point?]
Thanks for the clarification.
> Alan Robertson <alanr at unix.sh>
> "Openness is the foundation and preservative of friendship... Let me
> claim from you at all times your undisguised opinions." - William
> Linux-HA-Dev: Linux-HA-Dev at lists.linux-ha.org
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