NCP-DB Practice Test

Explanation:
An NDB compute profile defines the CPU and memory resources for the database server VMs that are provisioned using NDB. It does not include any information about the network, domain, or software of the database server VMs. Those are specified in separate profiles, such as network profile, domain profile, and software profile.

Explanation:
The log frequency in the Era IJI for log catchup operation can be configured to as low as 5 minutes. This allows the system to capture changes to the database at a high frequency, enabling more precise point-in-time recovery options. However, it’s important to note that a higher frequency of log catchup operations can lead to increased system load. Therefore, the optimal frequency may vary depending on the specific requirements and capabilities of your system12. Please refer to the Nutanix Database Automation (NCP-DB) Learning documents for more detailed information.

Explanation:
The Nutanix Era platform provides a feature called Time Machine, which is designed to manage the lifecycle of database copies and clones1. When a new table is added to the source database, the administrator should perform a Log Catch-up using the source database’s Time Machine. This action ensures that the Time Machine captures the latest state of the source database, including the newly added table1. After performing the Log Catch-up, the administrator should refresh the clone database. The refresh operation updates the clone with the latest state captured by the Time Machine, thereby publishing the new table to the clone1.

Explanation:
A Time Machine is a core construct of the copy data management service in NDB that captures and manages the data of a database to deliver a recovery point objective (RPO) SLA. A Time Machine can enter a Frozen state for various reasons, such as database de-registration, snapshot or log catchup failures, or manual intervention. When a Time Machine is in a Frozen state, it stops taking new snapshots and log backups, and cannot perform any clone, refresh, or restore operations. To resume the normal operation of a Time Machine, it must be thawed by resolving the root cause of the freeze. One of the common causes of a Time Machine freeze is when the database is de-registered from NDB without removing the Time Machine. This can happen when the administrator wants to move the database to a different NDB instance or cluster, or when the database is accidentally de-registered. In this case, the Time Machine becomes orphaned and frozen, and cannot be used for any operations. To complete the request to refresh a database clone from a new manual snapshot, the administrator must first re-register the database in NDB using the same database name and ID as before. This will automatically thaw the Time Machine and resume its operation. The administrator can then create a new manual snapshot from the Time Machine and use it to refresh the database clone. The other options are not correct, as they either require unnecessary steps or do not address the root cause of the freeze.

Explanation:
When provisioning a PostgreSQL HA Instance using NDB, the minimum and maximum number of DB server VMs that can be deployed in a cluster are 2 and 4, respectively. A PostgreSQL HA Instance is a database instance that provides high availability and fault tolerance for PostgreSQL databases using the Patroni framework. Patroni is a Python-based tool that manages PostgreSQL configuration and performs automatic failover and switchover operations. Patroni relies on a distributed consensus store, such as etcd, Consul, or ZooKeeper, to store and synchronize the cluster state and leader information. NDB supports etcd as the consensus store for PostgreSQL HA Instances. NDB allows the administrator to provision PostgreSQL HA Instances with different sizes and configurations, such as small, medium, large, or custom. The size of the PostgreSQL HA Instance determines the number of DB server VMs, the number of etcd nodes, the CPU, memory, and disk resources, and the replication factor of the database. The minimum number of DB server VMs for a PostgreSQL HA Instance is 2, which corresponds to a small size instance. This configuration provides one leader and one follower DB server VM, and one etcd node. The maximum number of DB server VMs for a PostgreSQL HA Instance is 4, which corresponds to a large size instance. This configuration provides one leader and three follower DB server VMs, and three etcd nodes. The other options are not valid for a PostgreSQL HA Instance, as they either do not provide enough redundancy or exceed the supported limit of DB server VMs.