>AVS is filesystem, database and application agnostic. AVS has no >real knowledge that the volumes being replicated are in use, which >is why AVS can replicate UFS, QFS, ZFS, single node Oracle, Sybase >and other Solaris supported data services.
I'm not sure how your points relate to the points I'm raising. For example, DRBD is also filesystem, database and application agnostic. In fact, DRBD depends on that design to replicate any block-based Linux filesystem, even ZFS running on Linux FUSE. DRBD does have knowledge that the volumes being replicated are in use. It sits under the filesystem so that it can intercept I/O and redirect it to other system and vice versa if the primary system has failed. AVS seems to have this ability as well according to page 60 of the administration guide, which describes its ability to substitute the secondary's volumes for the primary one, so it must have this knowledge as well. >This relationship between AVS and the data service it is >replicating, is unfortunately left to those that choose to deploy >AVS. AVS is a technology, to be used in combination with other data >services, as AVS by itself is not a solution. I don't see what an admin could do to control its behavior. What facility can make it change the designation of primary and secondary on the fly? This is trivial to do in DRBD. In fact, high availability in Linux essentially depends on it. To me, the real difference was the conscious, design decision to have AVS rigged to consider the primary and secondary as fixed designations and to assume that admins will always want replication in one direction. Perhaps, in the future, you'll consider reevaluating this approach. That being said, I'm wondering whether I've identified three bugs in AVS. It doesn't make sense to me in any circumstance that turning on autosync on the primary should not be a state shared by the secondary, that it must be turned on both systems, and that switching to logging mode should cause the state of autosync to be misreported as off (it can't, of course, autosync in this mode, but that's an action [autosynchronizing], not a property) or that the output of dsstat on the two systems should ever disagree. -- Maurice Volaski, [EMAIL PROTECTED] Computing Support, Rose F. Kennedy Center Albert Einstein College of Medicine of Yeshiva University _______________________________________________ storage-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/storage-discuss
