On Wed, 2008-09-10 at 18:37 -0400, Maurice Volaski wrote: > >On Wed, 2008-09-10 at 15:00 -0400, Maurice Volaski wrote: > >> >On Wed, 2008-09-10 at 14:36 -0400, Maurice Volaski wrote: > >> >> A disadvantage, however, is that Sun StorageTek Availability Suite > >> >> (AVS), the DRBD equivalent in OpenSolaris, is much less flexible than > >> >> DRBD. For example, AVS is intended to replicate in one direction, > >> >> from a primary to a secondary, whereas DRBD can switch on the fly. > >> >> See > >> >> http://www.opensolaris.org/jive/thread.jspa?threadID=68881&tstart=30 > >> >> for details on this. > >> > > >> >I would be curious to see production environments "switching" direction > >> >on the fly at that low level... Usually some top-level brain does that > >> >in context of HA fail-over and so on. > >> > >> By switching on the fly, I mean if the primary services are taken > >> down and then brought up on the secondary, the direction of > >> synchronization gets reversed. That's not possible with AVS because... > >> > >> >well, AVS actually does reverse synchronization and does it very good. > >> > >> It's a one-time operation that "re-reverses" once it completes. > > > >When primary is repaired you want to have it on-line and retain the > >changes made on the secondary. > > Not necessarily. Even when the primary is ready to go back into > service, I may not want to revert to it for one reason or another. > That means I am without a live mirror because AVS' realtime mirroring > is only one direction, primary to secondary.
This why I tried to state that this is not realistic environment for non-shared storage HA deployments. DRBD trying to emulate shared-storage behavior at a wrong level where in fact usage of FC/iSCSI-connected storage needs to be considered. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
