[PVE-User] HA question

Thomas Lamprecht t.lamprecht at proxmox.com
Thu Oct 6 11:27:17 CEST 2016


On 10/06/2016 11:01 AM, Eneko Lacunza wrote:
> Hi,
> About the "disable" thing, wouldn't it be much clearer and less prone 
> to confusion to rename it to "disable-ha-and-stop"? And I guess, 
> "enable-ha-and-start"?

for me not, as its not disabling ha but disabling the service  (ok, I'm 
really biased, I know :) )

Maybe adding something that a user understands easier that as soon he adds
it to HA its managed by HA, and he does not make action to control the HA
manager but tells the HA manager to take action on the service, e.g. disable
or enable it.

I'd propose adding a tooltip to the HA resource edit window which pops 
up if a
user changes the "enabled" status of a service.

Further adding there a Help button which links to the new built in 
to the respective chapter.

This should help avoiding situations were someone disables a VM because he
thinks that means disabling HA temporary.

I opened a bug report regarding

hope this will help a bit.


> El 06/10/16 a las 09:39, Thomas Lamprecht escribió:
>> On 10/06/2016 09:08 AM, Kevin Lemonnier wrote:
>>>> He wanted to remove it from HA managed but said to HA it should be
>>>> stopped, nothing to do with the stop/shutdown button confusion :)
>>> Yeah sorry about that, I hijacked this thread with my somewhat 
>>> un-related
>>> complaint, that's my bad :).
>> No worries, and I hope also that I didn't discourage any from giving 
>> feed back.
>> The ha-manager did not received that much feedback, besides obvious 
>> bug reports.
>> So thanks for yours.
>>> The HA enable / disable is a bit confusing, it just doesn't work as 
>>> you'd
>>> expect. Now that I used HA a lot more I get it, but it's a bit of a 
>>> trap
>>> when you are starting with HA, just like the fact that only one task 
>>> can
>>> be carried out at the same time on HA enabled VMs. I understood that 
>>> only
>>> a few weeks ago when gluster froze a VM and that stuck HA on a task 
>>> forever,
>>> took me a while to understand why I couldn't do anything about all 
>>> of the
>>> other VMs.
>> That's the nature of the finite state machine (FSM) in the HA 
>> manager, you
>> can be in only one state at a time.  We think one task per time is 
>> good for
>> HA as multiple at the same time can have side effects, which is not 
>> good.
>> We want that a service is always in a defined and if possible good 
>> state.
>>> Or why on some VMs the live migration has an output and for others 
>>> it doesn't,
>>> it's because for HA enabled VM you just add a task, the output is in 
>>> a separate
>>> task.
>> Yes that is can be confusing I guess, it came with the architecture 
>> of the
>> ha-manager.
>> The ha-manager has quite simple mechanics internal, this makes in 
>> generally
>> more stable (hopefully ;)).
>> When it was combined it with the rest of the PVE ecosystem we tried to
>> integrate it without much changes there, to avoid new bugs and new 
>> code to
>> maintain.
>> that lead to things like two task per real task as the interface has 
>> not to
>> care if it triggers a task for a ha-managed or non-ha VM.
>> For the double task list I have an idea in my head, I have to try it 
>> if it works and
>> evaluate it if the changes are justified.
>>> Maybe it'd be good to add a visual hint about that, you aren't actually
>>> stoping, starting or migrating a VM, you are just adding a task for 
>>> the HA to
>>> carry out later, and that's where you should look to see the output 
>>> ? Same thing
>>> in HA, the enable / disable tick box could maybe be labelled "keep 
>>> powered on" or
>>> something similar ?
>> The hint in the ha-managers task output is a good idea!:)
>> For the enable/disable things I'm hesitating, its good documented and 
>> from
>> the point of how the ha-manager works it makes sense, imo.
>> We talked internally about an "unmanaged" state in the FSM, it was 
>> just an
>> idea from my side and not a real need were here we decided against doing
>> it to let things be as simple as possible.
>> cheers,
>> Thomas
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