Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Thanks Digimer! I will learn more about DRBD's fencing mechanism. On Wed, Mar 2, 2016 at 12:10 PM, Digimer <lists at alteeve.ca> wrote: > On 01/03/16 08:56 PM, Mark Wu wrote: > > Hi Digimer, > > > > Thanks for your reply! > > > > Yes, I understand fencing can prevent split-brains. But in my case it > > maybe not sufficient. Let me clarify my use case. Basically, you can > > get the architecture from http://ibin.co/2YoKo5VOmRYn The app on each > > client server will do I/O via block interface directly instead using a > > cluster file system. Every client server need write access to all drdb > > volumes to build a VG group. But the application can guarantee that no > > two servers write to the same data area at the same time because it just > > writes to the data belonging to itself even when spli-brain happens. So > > merging data I mentioned before means just pull all newest data from > > different volumes together. > > > > For the suggestion of fencing, I think it still can cause somehow > > out-of-sync because the fencing is invoked by cluster management > > software, but in data plane the I/O could be done before the fencing > > happens. > > > > my understanding is that fencing is invoked by the cluster management > > software asynchronously. > > First; My experience is with 8.4, not 9. So caveat emptor. > > DRBD has its own concept of fencing; 'fencing; resource-and-stonith;' > and 'fence-handler "/path/to/some/script";'. If DRBD detects the peer > fail, it blocks IO and calls the fence handler immediately. Most often, > this handler passes the request up to the cluster manager and waits for > a success message. > > So no, DRBD will not fall out of sync. > > As for your use case; I honestly don't understand it. It looks rather > complicated. > > -- > Digimer > Papers and Projects: https://alteeve.ca/w/ > What if the cure for cancer is trapped in the mind of a person without > access to education? > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20160302/d2170e80/attachment.htm>