A request is received to refresh a database clone from a new manual snapshot. When the administrator attempts to create the new snapshot from the Time Machine, it is in a Frozen state. What causes a Time Machine to enter the Frozen state and what are the administrator's options to complete the request?
Answer(s): C
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.
Nutanix Certified Professional - Database Automation (NCP-DB) v6.5, Section 5 - Protect NDB- managed Databases Using Time Machine, Objective 5.1: Create, delete, and modify SLA retention policiesNutanix Database Management & Automation (NDMA) Course, Module 4: Nutanix Database Service (NDB) Data Protection, Lesson 4.1: Data Protection Overview, Topic: Time Machine Concepts Nutanix Support & Insights, TN-2101: Nutanix Database Service Time Machine Under the Hood, Section: Time Machine States and Transitions
Refer to the exhibit.An administrator attempts to provision their first clustered database environment with NDB. The operation fails with the Operation Error shown in the exhibit. Which database engine was being deployed during this operation?
Answer(s): B
The error message in the exhibit indicates that the operation failed during the "Create and Register Database Server VMs" step because "Provisioning of all the observers simultaneously took more than two hours." This type of error is associated with MySQL, as it involves observers which are a part of MySQL Group Replication, used for ensuring high availability1. The other options are not related to the error message, as they do not use observers or Group Replication for clustering.
1: Nutanix Database Automation (NCP-DB) course, Module 5: Database High Availability, Lesson 5.2:MySQL Group Replication, slide 7
Which two options can NDB leverage to refresh a database clone? (Choose two.)
Answer(s): B,C
NDB can leverage snapshots and transaction logs to refresh a database clone to the latest state of the source database. Snapshots are point-in-time copies of the database that are stored on the Nutanix cluster. Transaction logs are records of the changes made to the database after the snapshot was taken. NDB can use either snapshots or transaction logs, or a combination of both, to refresh a database clone. Cerebro logs and templates are not used for refreshing database clones. Cerebro logs are used for log catch-up operations, which are different from refresh operations. Templates are used for provisioning new databases, not for refreshing existing ones.
Nutanix Database Management & Automation (NDMA) course, Module 4, Lesson 4.3 - RefreshingClonesNutanix Support & Insights, Nutanix NDB User Guide v2.5, Clone Database Management
Which NDB feature collects logs and snapshots from databases?
The correct answer is B because the Time Machine feature of NDB collects logs and snapshots from databases and stores them in a distributed file system. The Time Machine enables the administrator to protect, clone, and restore databases using the SLA policies and the NDB UI or API. The Time Machine also manages the replication of database snapshots in an NDB multicluster environment. The other options are not correct because they describe different features or functions of NDB. Option A is not correct because Database Restore is an operation that uses the Time Machine to restore a source database or a clone to a previous point in time. Option C is not correct because SLA is a policy that defines the frequency and retention of database snapshots and logs. Option D is not correct because One-click Patching is a feature that allows the administrator to test, publish, and apply database patches using the NDB UI or API.
Nutanix Database Management & Automation (NDMA) course, Nutanix Certified Professional - Database Automation (NCP-DB) certification, Nutanix NCP-DB Certification Exam Syllabus and Study Guide, Nutanix Support & Insights
What happens to the primary member in a MongoDB Server Cluster during the NDB patching process?
Answer(s): D
According to the NDB documentation, the NDB patching process for MongoDB Server Cluster follows these steps1:NDB identifies the primary member of the MongoDB Server Cluster and patches it first. NDB triggers a failover to elect a new primary member from the remaining secondary members. NDB patches the former primary member, which becomes a secondary member after the failover.NDB patches the remaining secondary members one by one. NDB verifies the patching status and the cluster health. This process ensures that the MongoDB Server Cluster always has a primary member available to handle write operations, while minimizing the downtime and the impact on the cluster performance.
Nutanix Support & Insights, section "Patching a MongoDB Server Cluster"
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