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MongoDB Ops Manager


A lightweight program that provides an interface between your MongoDB processes and Ops Manager.
agent API key

A unique identifier that authenticates a project's MongoDB Agents to Ops Manager. A project can have multiple agent API keys.


See also:

application database

The dedicated set of MongoDB databases that store metadata for the Ops Manager installation and the managed MongoDB deployments.

authentication mechanism

A method to enable access to a MongoDB database. This is separate from authorization, which grants you permission to use certain actions on a MongoDB database.


The assisted management of MongoDB processes through the Ops Manager interface. The MongoDB Agents installed on your MongoDB hosts allow you to deploy, configure, and update MongoDB processes directly from Ops Manager.


See also:

Automation Agent

The lightweight component that had automated common management tasks. The Automation Agent runs on every server that ran a mongod or mongos.


This has been replaced with the MongoDB Agent.

backing databases

The collective term for the sets of MongoDB databases that support an Ops Manager deployment: the application database and the backup database(s).

Backup Agent

The lightweight component that had run within your data center and backed up MongoDB processes via the MongoDB wire protocol. No direct file system access was needed.


This has been replaced with the MongoDB Agent.

backup blockstore database
The database that stores your snapshots. The database is also referred to simply as the blockstore. The blockstore uses a storage format that parses a snapshot into smaller chunks that allow Ops Manager to manage snapshot changes. You can administer blockstores from the Snapshot Storage. The blockstore is one type of Backup Database.
backup cursor
A tailable cursor pointing to a list of backup files. Starting with FCV 4.2, Ops Manager uses backup cursors instead of head databases.
Backup Daemon

The Ops Manager component that creates and manages backups by maintaining head databases and snapshots for FCV 4.0 and earlier. Starting with FCV 4.2, onprem uses backup cursors instead of head databases.

Backup Database

The set of databases where onprem stores backup data. This includes the Oplog Store Database and any backup blockstore database or S3 Snapshot Store metadata database deployed.


See also:

backup job

The Ops Manager process that backs up MongoDB deployments.

For FCV 4.0 and earlier, the Backup Daemon stores backups locally as head databases. A sharded cluster will have a different head database for each shard.

For FCV 4.2 and later, the WiredTiger storage engine takes snapshots of your deployment using backup cursors to allow point-in-time copying of the WiredTiger files. Applications can continue read and write operations on the database while WiredTiger takes the snapshot.

You can re-assign backup jobs among Backup Daemons.


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The collection of jobs needed to restore a sharded cluster: one job for each shard and one job for the config server.

Replica set restore jobs do not use batches.

A MongoDB document that stores the compressed contents of a 64 KB to 16 MB slice of the data and metadata of a file included in a snapshot. In dividing the snapshot, Ops Manager can back up data block by block instead of writing whole new copies of a snapshot.

A point in time between snapshots to which you can restore a sharded cluster. Ops Manager must stop the balancer each time it creates a checkpoint. Ops Manager doesn't require checkpoints and disables checkpoints by default.


You may use checkpoints for clusters that run MongoDB with Feature Compatibility Version of 4.0 or earlier. Checkpoints were removed from MongoDB instances with FCV of 4.2 or later.


See also:

In Ops Manager, cluster can refer to either a replica set or sharded cluster.
conf call
A request from a MongoDB Agent to Ops Manager to get the latest configuration for that Agent's project including the nodes to which the Agent connects and what data to back up.
custom snapshot

A backup of the state of your MongoDB deployment at a point in time between stored snapshots. Ops Manager builds a custom snapshot by applying oplog data to a stored snapshot.



A process that eliminates redundant data. This data can be additional copies of database or file system documents or redundant data within those documents at the block level when written to a storage medium like spinning or solid state disks. Only unique documents or blocks are written to a storage medium. This process usually applies to backups or data archiving.


Each recipient in an email system may have their own copy of an email sent to the whole company. With deduplication, all copies of this except one are replaced with pointers to a single stored copy before backing up the email system. This effectively reduces the amount of storage capacity needed to back up this one email by 99 percent.

Usually refers to all the MongoDB processes that run within an Ops Manager project. Deployment can also refer to a specific set of MongoDB processes, such as a specific sharded cluster or replica set.
dirty bytes
Data that has been updated in the WiredTiger cache but not flushed to disk.
excluded namespace

A database or collection that Ops Manager will not back up, as designated by its namespace.


File System Store
A directory on a server that stores your database backup snapshots as files. You can administer file system storage from the Snapshot Storage.
A job that removes unused blocks on a blockstore and that can move blocks from one blockstore to another. You can view and manage grooms from Grooms and Groom Priority.

A distinct set of MongoDB processes and Ops Manager users. Synonymous with project.


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head database

The copy of a backed-up deployment stored on the Backup Daemon's server. The daemon maintains a head database for each shard or replica set it backs up and creates periodic snapshots. The Daemon stores the head databases in the head directory.

Starting with FCV 4.2, onprem uses backup cursors instead of head databases.

head directory
The dedicated disk partition on the Backup Daemon's host where the Backup Daemon stores the head databases. The daemon writes to this directory as the mongodb-mms user.
A physical machine, virtual machine, or container that serves one or more MongoDB processes.
initial sync

The MongoDB operation that replicates data from an existing replica set member to a new member. Ops Manager uses initial sync when creating a new head database.


See backup job.

A string that contains the information necessary to connect from Ops Manager to Atlas during a Live Migration from an Ops Manager deployment to a deployment in Atlas.

When you are ready to live migrate data from an Ops Manager deployment, you generate a link-token in Atlas and then enter it in your Ops Manager organization's settings. You use the same link-token to migrate each deployment in your Ops Manager organization sequentially, one at a time.

You can generate multiple link-tokens in Atlas. Use one unique link-token for each Ops Manager organization.

migration host

A dedicated server with its own specially-configured MongoDB Agent configured for live migration. You run the Live Migration (push) process on the migration host to migrate your MongoDB deployment to Atlas.

MongoDB Agent

A lightweight agent that can monitor, manage, and back up your MongoDB databases.


See also:


The real-time reporting, visualization, and alerting of the state of your MongoDB processes.


See also:

Monitoring Agent

The lightweight component that had run within your data center and monitored your MongoDB processes via the MongoDB wire protocol. No direct file system access was needed.


This has been replaced with the MongoDB Agent.


The combination of the database name and collection name:

oplog slice

A compressed batch of entries for the tailed oplog of a backed-up shard or replica set. The MongoDB Agent creates an oplog slice and sends it to Ops Manager, which stores it in the Oplog Store Database.

For FCV 4.0 and earlier, the Backup Daemon retrieves the slice and applies it to the associated head database.

For FCV 4.2 and later, onprem retrieves the slice and stores it in the Oplog Store Database.


See also:

Oplog Store Database

The database where Ops Manager stores oplog slices before applying them to a deployment's backup.


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Ops Manager Application

The main Ops Manager component. The application provides the user interface for managing MongoDB deployments and provides endpoints for MongoDB Agents to transmit data.

Ops Manager HTTP Service

The interface through which the MongoDB Agent communicates with Ops Manager.

A data transmission that the MongoDB Agent sends to Ops Manager to confirm that the Agent and its MongoDB processes are running and reachable.
point-in-time restore

A database restoration that captures the state of your data at a moment in-between snapshots. Point-in-time restores take longer to perform than snapshot restores.



An instance of MongoDB running on a given host and port. The MongoDB database process is mongod. MongoDB also uses the mongos process to route operations in the sharded clusters.


A distinct set of MongoDB processes and Ops Manager users. Synonymous with group.


See also:

Public API key
A unique identifier that authenticates an Ops Manager user through the Ops Manager Administration API. The key belongs to the user, as opposed to the agent API key, which belongs to the project.
queryable backup

A feature provided by Ops Manager in which Ops Manager quickly and securely makes a given snapshot accessible over a MongoDB connection string. You can use the connection string with standard MongoDB tools such as mongosh or mongodump to access the snapshot for read-only operations.

Queryable backups start up quickly regardless of the snapshot's total data size. They are uniquely useful for restoring a small subset of data, such as a document that was accidentally deleted, or reading out a single collection with mongodump.

Recovery Point Objective
The maximum tolerable age of backup files that must be recovered from storage for normal operations to resume after a failure or disaster occurs.
Recovery Time Objective
The maximum tolerable length of time that a system can be offline after a failure or disaster occurs.

The permissions granted to an Ops Manager or MongoDB user.


See also:

rolling restart

A technique used to maintain cluster availability during maintenance periods by updating nodes in a replica set one-by-one, always maintaining a primary node, until all nodes are updated.

S3 Snapshot Store

An s3 bucket in aws that stores your database backup snapshots as blocks. You can administer s3 blockstore storage from the Snapshot Storage.

A physical or virtual machine that serves one or more MongoDB processes.

Single backup of your data that Ops Manager captures at a specific interval and stores as a snapshot in one of the following locations:

Ops Manager creates snapshots in different ways depending on the fcv-link of the MongoDB database:

  • For fcv-link 4.0 or earlier, Ops Manager created snapshots from database copies kept on head databases.

  • For fcv-link 4.2 or later, Ops Manager creates snapshots from secondaries.

The Snapshot Frequency and Retention Policy determines the interval for taking snapshots and how long to store them.

snapshot frequency and retention policy

The schedule for how often to take snapshots and how long to store them.

snapshot store

The location where your snapshots are stored. There are multiple types of snapshot stores, including:

storage engine

The database storage engine manages how data is stored on disk. MongoDB versions 3.0 and later offer multiple storage engines.


See also:

sync store
During inital sync of a backed-up deployment, Ops Manager briefly stores slices of the backed-up deployment in a temporary sync store on the Oplog Store Database. Ops Manager uses the storage while streaming slices to the Backup Daemon.
version manifest
List of all released MongoDB versions that a particular version of Ops Manager supports. Ops Manager uses this list if running in local mode.
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