How much free space is required on each Centera node to perform an upgrade from 4.2.0 to 4.3.x?

The Centrastar upgrade only writes to the operating system partitions on a node.  In unix/Linux parlance, we are talking about the "/" "/usr" "?var" partitions to name a few.  The application data is stored on other partitions that are not touched during a Centrastar upgrade.

There are pre-upgrade checks that are run by the upgrading engineer to check the health and upgrade-suitability of the cluster.  One of these checks involves checking these OS partitions for required free-space.  If the checks indicate there is not enough free-space, the CE would engage an FSS or the Centera support lab to address the issue (again, leaving the data stored on the Centera untouched).

So a node that is showing as "completely full" in the Centera Viewer would still be able to be upgraded without issue.