[Sheepdog] [PATCH 2/2] sheep: don't skip notify event

[Liu Yuan]

On 04/01/2012 10:21 AM, Liu Yuan wrote:

> On 03/31/2012 06:20 PM, MORITA Kazutaka wrote:
> 
>> This change means that all notify events (e.g. vdi creation) block
>> membership change events.  I think it is not good to block them so
>> long time.
>>
> 
> 
> No, VDI creation and deletion doesn't block membership change events,
> since current two patches allows confchg to be tackled immediately once
> it happens.
> 
> We do VDI create & delete in a loop during 60 nodes leaving in a cluster
> with large set of nodes, and don't see any evidence that confchg is blocked.
> 
> I think the previous strategy that allow IO requests block both VDI and
> node event is non-sensible, causing both VDI operation and node event to
> be delayed as much as more than several minutes. This is definitely
> intolerable for users that do VDI operation and Guests requests are
> easily failed during such a long internal.
> 


to be precisely, the delay for VDI operation is several minutes, but for
recovery process could be up to hours, since adjacent recoverys hardly
overlap one another(it depends how many nodes join/leave in one go)

Thanks,
Yuan

> Thanks,
> Yuan
> 
>> However, as you say, we need to order the shutdown event with
>> membership change ones.  Currently, I don't have a better idea, so it
>> is okay to me to merge this patch, but, if possible, I'd like to see a
>> better fix for it.
> 
>