[Drbd-dev] DRBD-8: handling of concurrent writes with two primaries

[Lars Ellenberg]

/ 2006-08-16 16:54:03 -0400
\ Graham, Simon:
> OK, so I was slightly wrong here:
> 
> > 2. If the UNIQE flag is set, then I don't see how the partner node
> > will make any progress - you never send an Ack and do not disconnect
> > - if the partner also sees the conflict then he will do the Discard
> > msg processing, but I don't think this is guaranteed - I'm probably
> > missing something, but if the partner gets the request and _then_
> > issues a write to the same location, I don't think it will do the
> > right thing... the partner will simply discard and you are left
> > hanging...
> 
> Since I've found the code that checks for collision on the write side
> and adds the info to the list. I still think the other issue applies
> (Ack and Data can be re-ordered which means there are cases where you
> wont wait for the outstanding req to complete when you really should)...

hmmm.
did you read
 http://www.drbd.org/fileadmin/drbd/publications/drbd8_wpnr.pdf
can you point out what we were missing there?

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