On Sun, Dec 27, 2015 at 01:26:15PM +0800, Mia Lueng wrote: > How does epoch works? I have examined the source code. when primary > recieves a bio with bi_size=0 or bio num > MAX_EPOCH_SIZE or idle > time exceeds limit , there will be a P_BARRIER packet triggered?
Yes, that too. But the important one is: > > Basic idea is: whenever we complete something to upper layers, > > we bump an atomic epoch counter. > > Anything sumitted within one epoch cannot possibly depend on > > something else within that same epoch. > > So within such an epoch, reordering is allowed. > > "on the wire", epochs are separated by "DRBD barriers". > > Receiving side uses drain/flush/barrier (depending on configuration) > > to make sure anything from a previous epoch is on stable storage > > before starting to submit for the next epoch. -- : Lars Ellenberg : http://www.LINBIT.com | Your Way to High Availability : DRBD, Linux-HA and Pacemaker support and consulting DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed _______________________________________________ drbd-user mailing list [email protected] http://lists.linbit.com/mailman/listinfo/drbd-user
