[DRBD-user] Primary/Primary : how put a node in outdate mode ?

Dominique Fournier dominique.fournier at grenoble.cnrs.fr
Mon Feb 4 12:34:41 CET 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Lars Ellenberg wrote:
> On Mon, Feb 04, 2008 at 12:08:41PM +0100, Dominique Fournier wrote:
>> Lars Ellenberg wrote:
>>> On Wed, Jan 30, 2008 at 12:28:01PM +0100, Dominique Fournier wrote:
>>>> Hello,
>>>>
>>>> I use a drbd 8.2.4-1, on a Debian 2.6.23-1-amd64 machine. The cluster 
>>>> should be in primary/primary mode with OCFS2 to support services on both 
>>>> nodes.
>>>>
>>>> It work really well under normal work.
>>>>
>>>> When the drbd link drops, I would like :
>>>> - The first node continue to work as Primary (with Waiting For Connection)
>>>> - The second node go to Outdate mode.
>>>>
>>>> When the link should goes up, the Secondary do a sync diff and after I 
>>>> can put it primary again, and restart OCFS and my services.
>>>>
>>>> I wrote a drbd-peer-outdater which know on which node it is launched.
>>>>
>>>> My problem is :
>>>> How can I put the second node in Outdate state immediately without 
>>>> passing it in Secondary mode ?
>>> you can't.
>>>
>>>> I can't pass it in Secondary because OCFS is mounted and dead services 
>>>> are connected to partition. I can't kill services nor OCFS because drbd 
>>>> is idle.
>>> and DRBD can't do anything about that.
>>>
>>> the OCFS2 way of dealing with this sort of problems is "SMITH",
>>> which translates to "shoot myself in the head" (compare with "STONITH").
>>> you could try to do a user space handler for these events,
>>> which resets the box (instead of or in addition to the outdate).
>>>
>>>
>> Thanks for your response.
>>
>> I dont't find any docs on this on OCFS2 but I will ask to their 
>> mailling-list.
> 
> it is nothing configurable there.
> the handler would be the DRBD outdate-peer handler,
> and _you_ would need to write one that would do the shooting.
> 
> I just mentioned that this would be the typical thing OCFS2 would do.
> when you had a _shared_ disk (not two replicated ones providing similar
> semantics) and OCFS2 could no longer see the disk, it would typically
> panic the box.
> 
> so for what you suggested above, such behaviour could possibly be
> implemented using DRBDs handlers, you just have to make them do that.
> 

Ah OK.

Thanks for the comment ! I will do that.

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