User`s guide

334 Copyright © Acronis, Inc., 2000-2010
 Server 3 uses storages B, C, D
The VA can be deployed to either C or D. If there is no storage shared by all the servers, you can
import the VA manually into any of the hosts. This will work, but backup performance will be far from
optimal.
After deployment, the agent virtual appliance can appear on any of the hosts included in the cluster,
depending on how the load balancing is configured.
Moving the agent VA around the cluster
The agent’s work is not affected when the Distributed Resource Scheduler (DRS) migrates the virtual
appliance to another host.
Creating a cluster of servers that already have agents
It is recommended that you remove Agents for ESX/ESXi from all but one of the servers. Retain the
agent whose VA resides on the shared storage. Restart the VA so that it becomes aware of the
cluster.
7.1.4.5 Support for VM migration
This section informs what you can expect when migrating virtual machines within a datacenter using
vCenter Server migration options. Performance considerations apply to both "hot" and "cold"
migration.
VMotion
VMotion moves a virtual machine's state and configuration to another host while the machine's disks
remain in the same location on shared storage. VMotion is fully supported for both Agent for
ESX/ESXi Virtual Appliance and the virtual machines being backed up by the agent. Migration of
either the virtual appliance or a machine can take place during backup.
Storage VMotion
Storage VMotion moves a virtual machine disks from one datastore to another. Migration of Agent
for ESX/ESXi Virtual Appliance with Storage VMotion is possible unless a backup or recovery is in
progress. During migration, the agent postpones any backup that has to start. It starts the backup
after the migration has been completed.
Migration of a virtual machine with Storage VMotion during backup is possible, but the backup may
fail or succeed with warnings. The agent will not be able to delete the snapshot taken before
migration because the machine is gone. To avoid this situation, do not migrate a virtual machine until
its backup is completed.
Performance considerations
It is critical to understand that backup performance degrades when Agent for ESX/ESXi does not have
direct access to the storage where the backed up disks are. In this case, the agent cannot attach the
disks. Instead, it obtains data from these disks through LAN. This process is much slower than
obtaining data from directly attached disks.
So the best practice is that Agent for ESX/ESXi Virtual Appliance be hosted on a host for which all
shared storages of the cluster are accessible. In this case, backup performance remains optimal,
wherever (within the shared storages) a virtual machine or the virtual appliance migrates. Once a
machine migrates to a local storage of a different host, its backups will run slower.