Upgrading software on a pair of nodes in a clustered environment

An article comprising:

• a non-transitory machine-readable medium that stores executable instructions to upgrade software on nodes in a clustered environment, the instructions causing a machine to:
• terminate processes on a first DPA in a first cluster before upgrading the software on the first DPA, the first DPA being used in a data protection system and configured to replicate a first storage volume at a production site to a second storage volume at a replication site, the first cluster being located at the production site and comprising the first and a second DPA, the first DPA and the second DPA connected to the first storage volume and the second storage volume by a network;
• set a first site control field in a first DPA upgrade object to indicate that the first DPA may not take control of the first cluster, the first DPA upgrade object being stored on the first storage array and associated with the first DPA, the first DPA upgrade object comprising the first site control field and a first version field indicating a version of software on the first DPA;
• upgrade the software on the first DPA to a first version from a second version;
• run the processes on the first DPA after upgrading the software on the first DPA to the first version;
• determine whether the second DPA in the first cluster is about to upgrade to the first version of software by reading a second upgrade status object stored on the second DPA;
• change the first site control field in the first DPA upgrade object to indicate that the first DPA may take control of the first cluster if the upgrade status object indicates that the second DPA is upgrading to the first version after reading the second upgrade status object stored on the second DPA;
• transfer site control of the first cluster from the second DPA in the first cluster to the first DPA in the first cluster after reading that the first site control field indicates that the first DPA may take control of the first cluster;
• and
• upgrade the software on the second DPA to the first version of software after the transferring of site control of the first cluster from the second DPA to the first DPA.

A first data protection appliance (DPA) in a first cluster comprising:

• circuitry configured to:
• terminate processes on the first DPA in the first cluster before upgrading the software on the first DPA, the first DPA being used in a data protection system and configured to replicate a first storage volume at a production site to a second storage volume at a replication site, the first cluster being located at the production site and comprising the first and a second DPA, the first DPA and the second DPA connected to the first storage volume and the second storage volume by a network;
• set a first site control field in a first DPA upgrade object to indicate that the first DPA may not take control of the first cluster, the first DPA upgrade object being stored on the first storage array and associated with the first DPA, the first DPA upgrade object comprising the first site control field and a first version field indicating a version of software on the first DPA;
• upgrade the software on the first DPA to a first version from a second version;
• run the processes on the first DPA after upgrading the software on the first DPA to the first version;
• determine whether the second DPA in the first cluster is about to upgrade to the first version of software by reading a second upgrade status object stored on the second DPA
• change the first site control field in the first DPA upgrade object to indicate that the first DPA may take control of the first cluster if the upgrade status object indicates that the second DPA is upgrading to the first version after reading the second upgrade status object stored on the second DPA;
• transfer site control of the first cluster from the second DPA in the first cluster to the first DPA in the first cluster after reading that the first site control field indicates that the first DPA may take control of the first cluster;
• and
• upgrade the software on the second DPA to the first version of software after the transferring of site control of the first cluster from the second DPA to the first DPA.