With the help of multiple chunkservers and good goals, files can be stored multiple times. Therefore, a certain level of high availability on a file-level can be achieved easily.
In addition, it is important to know that per default, the master service only can be active in a master role on one node at the time. If this node fails, e.g. because of broken hardware or out-of-memory situations, the current master has to be demoted (if still possible) and an existing shadow has to be promoted manually.
If the failover happens automatically, a good state of high availability is achieved on a service level. Thus the term “High Availability” refers to keeping the master role alive when everything goes down under.
