Hi Ashu, Concerning migration it would be triggered by a "clrg switch" command, although migration or live migration would be resource specific. By this I mean that when a "DomU resource" is registered with OHAC, the switchover method will be determined, i.e. migration, live migration or just failover (stop/relocate/start). However whatever method is chosen, the appropriate method would be triggered by a "clrg switch" and implemented by the HA-Xen agent.
There are some restrictions for migration, in that the DomU's virtual block devices (VBD) need to be accessible by both nodes that are participating in such a migration. One could think of "accessible" in terms of a global file system. If a Zpool/ZFS was being used by a DomU's VBD list, then that Zpool/ZFS would only be available to both nodes participating in a migration and not accessible. In this regard, it's my belief that migration or live migration would not be possible for a DomU using a Zpool/ZFS VBD. However, my belief my change once we are engaged with the Xen community. Concerning placing a DomU offline. For those familiar with Solaris Cluster, this is akin to RG_affinities and in particular a strong negative affinity. For those not familiar with this terminology please see http://blogs.sun.com/SC/entry/how_does_sun_cluster_decide for an informative article about affinities. With the above in mind, "Allow for important DomUs where lesser DomUs are "offlined" means that using HA-Xen with OHAC and assuming a 2-node cluster, under normal operations both nodes could be running several domUs. However, some DomUs maybe more important than others and in the event of a node failure it maybe desirable to favor an important DomU over another DomU. Utilizing RG_affinities it would be possible to offline a less important DomU in favor or an important DomU to free up system resources so that upon failover the important DomU maintains a specific service level. In summary, this is an important feature and one that already exists within Solaris Cluster and therefore OHAC. However, in my opinion perhaps the greatest strength of RG_affinities is the knowledge that one could utilize all nodes thereby not having any idle nodes with the comfort of knowing that in the event of a node failure, OHAC + HA-Xen will favor important DomUs over lesser DomUs when using RG_affinities. Many thanks for your support with the remainder. Regards Neil -- This message posted from opensolaris.org
