Erast Benson wrote: >> Uh, no, DRBD addresses only replication. Linux-HA (aka Heartbeat) >> address availability. They can be an integrated solution and are to >> some degree intended that way, so I have no idea where your opinion >> is coming from. >> > > Because in my opinion DRBD takes some responsibility of management layer > if you will. Classic, predominant replication in HA clusters schema is > primary-backup (or master-slave) and backup by definition is not > necessary primary-identical system. Having said that, it is noble for > DRBD to implement role switching and not a bad idea for many small > deployments. >
The problem with fully automated systems for remote replication is that they are fully automated. This opens you up to a set of failure modes that you may want to avoid, such as replication of data that you don't want to replicate. This is why most replication is used to support disaster recovery cases and the procedures wrapped around disaster recovery also consider the case where the primary data has been damaged -- and you really don't want that damage to spread. It so happens that snapshots are another method which can be used to limit the spread of damage, so there might be an opportunity here. By analogy, in the Oracle world, RAC does not replace DataGuard. >> For replication, OpenSolaris is largely limited to using AVS, whose >> functionality is limited, at least relative to DRBD. But there seems >> to be a few options to implement availability, which should include >> Linux-HA itself as it should run on OpenSolaris! >> I disagree, there are many ways to remotely replicate Solaris systems. TrueCopy and SRDF are perhaps the most popular, but almost all storage arrays have some sort of system. In truth, there is little market demand for fully automated solutions at the OS level because of the reasons mentioned above. > > Everything is implementable and I believe AVS designers thought about > dynamic switching of roles, but they end up with what we have today, > they likely discarded this idea. > It is open source... -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
