HP StorageWorks Clustered Gateway (server/software bundle) 3.6.0 Windows Storage Server Edition Upgrade Guide (5697-7456, April 2008)

Chapter 2: Upgrade procedure 4
If the cluster is only partially upgraded, alerts raised by nodes running
3.6 will be improperly logged by nodes running 3.4. Also, until the entire
cluster is upgraded, many services that are run on 3.6 nodes must be run
as local system administrator.
Use Another Machine to Store All Backups
As part of the upgrade process, you will have to back up configuration
details and other important files before initiating upgrade. The section
'Backup the Existing Cluster' specifies all the files that will have to be
backed up. These files will have to be restored at a later stage during the
upgrade. Make sure all files are backed up on another node in the
network. If you back up the files on the same node, you will lose the
backup during the upgrade process, since the upgrade procedure deletes
the existing logical drives and creates new ones.