Designing High Availability Solutions with HP Serviceguard and HP Integrity Virtual Machines

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Offline VM Migration with Serviceguard
In the event of a VM host or guest failure, or if the user issues a cmhaltpkg/cmrunpkg command, this will trigger the
applications, OS and VM guest to halt and the VM guest package to start on its adoptive VM host cluster node where
the VM guest, its OS and applications are restarted. Note that:
• The VM guest and its applications are unavailable during this process
• All Serviceguard commands function normally using standard package failover operations
Online VM Migration without Serviceguard
In this situation, the user issues an hpvmmigrate command to begin the online migration process to move the source
VM guest to the target VM host. The online migration proceeds through the following phases:
• Phase 1—Perform migration compatibility checks and copy the VM guest configuration information to the target
VM host
• Phase 2—Perform a full VM guest memory copy to the target
• Phase 3—Quiesce I/O—queue new requests and wait for current I/Os to complete
• Phase 4—”Freeze” the VM guest execution and copy the remaining dirty memory pages to the target
• Phase 5—Completion—”Thaw” VM guest on the target and gradually catch-up the frozen time
Note that during the migration process:
• VM guest applications are fully operational except during the “freeze” period (which will average several seconds
depending on the activity within the VM at the time of the migration, the speed of the network connection, and the
amount of memory configured in the guest) with network packets being dropped during this time
• The source VM guest will continue operation if migration fails or is aborted by the user
Online VM Migration with Serviceguard
Online migration of a VM guest as a Serviceguard package is supported only when the storage for the guest’s
backing store is concurrently accessible to both the source and destination nodes for the migration, such as backing
stores on whole disks, shared LVM volume groups or on shared NFS file systems. To perform an online migration of a
VM guest as a Serviceguard package, the user executes the cmmovevpkg (SG-IVS toolkit) or hpvmsg_move (Integrity
VM Serviceguard toolkit) command that performs the following operations:
• Serviceguard VM guest package switching is disabled (i.e., monitoring and failover functions are not available);
however, the VM continues to run on the source VM host
• The VM guest is migrated to target VM host online using the hpvmmigrate command automatically invoked by the
toolkit command
• When migration is complete, VM guest package switching is re-enabled (i.e., Serviceguard monitors and can
failover the VM guest)
These toolkit commands have the advantage of performing online migration of VM guests protected by Serviceguard
with the benefit of minimizing both VM guest planned and unplanned downtime. In this case, VM guests can be
migrated online with minimal interruption during planned events while Serviceguard protects the VM guests from
unplanned failures during normal operation. Note that Serviceguard does not monitor or protect the VM guest during
the online migration process. However, the VM guest and its applications are fully available except during migration
process “freeze” time.
VM Guest Migration considerations
Offline VM Migration without Serviceguard
Used for:
• Moving VM configuration information while the VM is stopped and is not using source or target VM host resources
(for example, CPU, memory)
• Copying the VM host source local storage, logical volumes, or file-backed storage to the target VM host
• Moving a VM guest between source and target VM hosts with different processor types or Integrity VM software
versions that would prevent the use of online migration