By Tapan Avasthi-Oracle on Aug 24, 2016
One of the salient features for Oracle VM Server for SPARC guest domains is live migration, which allows you to transfer a running guest domain between different physical machines while maintaining continuous service to clients. For example, the administrator could relocate the guest domain to another cluster node without a disruption to clients, thereby freeing up the node for a planned outage.
Typically, Oracle Solaris Cluster resource types perform a switchover of a resource group from one node to another by stopping the application on the source node, and then starting it on the target node. However, for a resource group containing a resource of type SUNW.ldom, if the Migration_type extension property is set to MIGRATE, a typical switchover is not performed. Instead, an attempt to live-migrate the guest domain to the target node is performed.
In order to live-migrate a guest domain managed by a resource of type SUNW.ldom, assume the root role or a role that provides solaris.cluster.modify and solaris.cluster.admin authorizations to execute the following on any one node:
$ /usr/cluster/bin/clresourcegroup switch -n target_node ldom-rg
However, due to the dynamic nature of guest domains and possible change to the system configuration, there can be cases where a guest domain live migration does not complete successfully. For example, the target node resources, such as vCPU or memory, might not meet the minimum requirements for the guest domain to start on the target node. Alternatively, a change in the authentication mechanism might prevent a guest domain from starting on the target node.
Currently, the HA for Oracle VM Server for SPARC data service reacts to a failed live migration by reverting to a cold switchover between the nodes of the resource group. In such a scenario, live migration is canceled, followed by a stop of the guest domain on the source node and then a start of the guest domain on the target node. However, that behavior is disruptive to the clients.
Before performing live migration, ensure that the migration will succeed by performing a dry-run migration of the guest
domain. Do this before executing a switchover of resource group containing a
resource of type SUNW.ldom, where Migration_type=MIGRATE is set. To perform a dry-run migration, assume the root role or a role that has been
assigned the LDoms Management profile and execute the following
$ /usr/sbin/ldm migrate-domain -n -c domain-name target_host
$ echo $?
Starting with Oracle Solaris Cluster 4.3 SRU4, which introduces version 10 of the SUNW.ldom resource type, a resource of that resource type and version can abort the switchover of the resource group if live migration fails, and leave the guest domain running on the source node. During a planned outage, this would prevent any interruption to clients. To enable this feature, set the new extension property Abort_migration to TRUE. When set, a switchover of the resource group will only work if live migration is successful, otherwise it will interrupt the ongoing resource group switchover and keep the guest domain in the active state on the source node. During this period, it is expected to see a change of state for resource and resource group, only to come back to the Online state. However, during this transient state change the guest domain remains in the active state throughout and continues to provide services to clients.
To migrate an existing resource of type SUNW.ldom to resource type version 10 and set the Abort_migration extension property, assume the root role or a role that provides solaris.cluster.modify and solaris.cluster.admin authorizations and execute the following on any one node:
$ /opt/SUNWscxvm/util/rt_upgrade ldom-rs
$ /usr/cluster/bin/clresource set -p Abort_migration=TRUE ldom-rs
For more information, refer the following resources:
Oracle Solaris Cluster Data Service for Oracle VM Server for SPARC Guide
SUNW.ldom(5) Man Page
Oracle Solaris Cluster 4.3 Reference Manual
SSL Live Migration for HA for Oracle VM Server for SPARC
Configuring a Data Service for Oracle VM Server for SPARC by Using a Graphical Wizard
Oracle Solaris Cluster Engineering