The administrator should perform a rolling upgrade, applying the patch to the secondary members

first, followed by the primary member, to accomplish the task of patching a MongoDB server cluster

within an NDB environment. A rolling upgrade is a method of applying patches or updates to a

cluster without downtime or interruption of service. The administrator can use the NDB patching

feature to perform a rolling upgrade on a MongoDB server cluster, which consists of a primary

member and one or more secondary members that form a replica set. The NDB patching feature

allows the administrator to select the software profile version, the database parameters profile, and

the network profile for the patching operation. The NDB patching feature also automates the steps of

the rolling upgrade, such as:

Step 1: The administrator initiates the patching operation on the NDB instance, and selects the

MongoDB server cluster to be patched.

Step 2: The NDB instance verifies the prerequisites and compatibility of the patching operation, and

creates a pre-patch snapshot of the MongoDB server cluster.

Step 3: The NDB instance applies the patch to the first secondary member of the MongoDB server

cluster, and waits for the patching to complete successfully.

Step 4: The NDB instance verifies the status and functionality of the patched secondary member, and

repeats the patching process for the remaining secondary members of the MongoDB server cluster,

one at a time.

Step 5: The NDB instance performs a failover of the primary member to one of the patched

secondary members, and applies the patch to the original primary member.

Step 6: The NDB instance verifies the status and functionality of the patched primary member, and

performs a failback of the primary member to the original primary member, if desired.

Step 7: The NDB instance creates a post-patch snapshot of the MongoDB server cluster, and

completes the patching operation.

Performing a rolling upgrade, applying the patch to the secondary members first, followed by the

primary member, is the recommended and best practice method of patching a MongoDB server

cluster within an NDB environment, as it ensures the high availability, consistency, and performance

of the MongoDB server cluster and the databases.

Performing a rolling upgrade, applying the patch to the primary member first, followed by the

secondary members, is not a valid or feasible method of patching a MongoDB server cluster within

an NDB environment, as it would cause downtime, data loss, and inconsistency of the MongoDB

server cluster and the databases. Applying the patch to the primary member first would disrupt the

replication and synchronization of the MongoDB server cluster, and would require manual

intervention and recovery steps to restore the MongoDB server cluster to a functional state.

Applying the patch to all nodes at once is not a valid or feasible method of patching a MongoDB

server cluster within an NDB environment, as it would cause downtime, data loss, and inconsistency

of the MongoDB server cluster and the databases. Applying the patch to all nodes at once would

require shutting down the entire MongoDB server cluster, and would expose the MongoDB server

cluster and the databases to potential errors, failures, and corruption during the patching process.

Disabling the replica set while patching is not a valid or feasible method of patching a MongoDB

server cluster within an NDB environment, as it would cause downtime, data loss, and inconsistency

of the MongoDB server cluster and the databases. Disabling the replica set while patching would

break the replication and synchronization of the MongoDB server cluster, and would require manual

intervention and recovery steps to re-enable the replica set and restore the MongoDB server cluster

to a functional state.

Reference::

Nutanix Database Management & Automation Training Course, Module 5: Nutanix Era Operations,

Lesson 5.1: Nutanix Era Operations, slides 11-12, 15-16.

Nutanix Database Management & Automation Training Course, Module 5: Nutanix Era Operations,

Lesson 5.3: Nutanix Era Patching, slides 5-9.

Nutanix Database Management & Automation Training Course, Module 5: Nutanix Era Operations,

Lesson 5.4: Nutanix Era Patching Lab, slides 5-10.

Nutanix Database Management & Automation Training Course, Module 7: Nutanix Era

Troubleshooting, Lesson 7.1: Nutanix Era Troubleshooting, slide 6.