Review Available Ops Manager Metrics

Displays the following information:

• regular displays the average rate of regular asserts raised per second over the selected sample period.

• warning displays the average rate of warnings per second over the selected sample period.

• msg displays the average rate of message asserts per second over the selected sample period. These internal server errors have a well-defined text string. MongoDB Atlas logs stack traces for these.

• user displays the average rate of user asserts per second over the selected sample period. This metric includes asserts that a user generates, such as out of disk space or duplicate key errors.

Monitor asserts to track how many errors occur while trying to read or write data. Check the server logs to identify the source of any errors.

Displays the following information:

• readInto displays the average rate of bytes per second read into WiredTiger's cache over the selected sample period.

• writtenFrom displays the average rate of bytes per second written from WiredTiger's cache over the selected sample period.

Monitor cache activity to track the read and write throughput of the WiredTiger storage engine cache.

Displays the following information:

• cache fill ratio measures how full the cache is. Ops Manager calculates this value by dividing the number of bytes currently in the cache by the maximum number of bytes configured and represents the result as a percentage. A cache fill ratio close to 100% indicates that the query working set is larger than the configured cache size. Increasing the cache size can reduce disk I/O.

• dirty fill ratio represents the proportion of dirty bytes (pages modified in memory but not yet written to disk) relative to the total cache. A high dirty fill ratio indicates that a significant amount of data is waiting to be flushed to disk, which can impact performance. Monitor this metric for write-heavy workloads to ensure data durability.

Monitor cache ratio to determine whether the cache size is sufficient for the current workload.

Displays the following information:

• used displays the number of bytes currently in the WiredTiger cache.

• dirty displays the number of tracked dirty bytes currently in the WiredTiger cache.

Monitor cache usage to determine whether the WiredTiger cache is approaching capacity.

Displays the following information:

• total databases displays the total number of non-system databases.

• total collections displays the total number of collections across all non-system databases.

• total views displays the total number of views across all non-system databases.

• total indexes displays the total number of indexes across all non-system collections.

Monitor catalog counts to prevent an excessive number of databases, collections, views, or indexes from causing startup failures.

Displays the following information:

• connections net increase displays the rate per second of the net increase in connections.

• connections net decrease displays the rate per second of the net decrease in connections.

• connections created displays the rate per second of connections created.

Monitor connection rate to track how quickly connections are being created or removed.

Displays the total number of active connections to the deployment. Each connection uses its own thread stack, so a large number of connections can result in significant RAM usage.

Monitor connections to determine whether the current connection limits are sufficient.

Displays the following information:

• totalOpen displays the number of cursors that the server is maintaining for clients. Since MongoDB exhausts unused cursors, this value is usually small or zero. However, if there is a queue, stale tailable cursors, or a large number of operations, this value might rise.

• timedOut displays the average rate of cursors that have timed out per second over the selected sample period.

Monitor cursors to close unnecessary cursors and reduce the timeout configuration in the application.

Displays the following information:

• storageSize displays the sum total compressed on-disk storage space allocated for document storage across all databases.

• logicalDataSize W/System displays the sum total uncompressed size in bytes of the document data (including the padding factor) across all databases including system databases.

• logicalDataSize displays the sum total uncompressed size in bytes of the document data (including the padding factor) across non-system databases.

• indexSize displays the sum total logical size in bytes (including prefix compression) of the index data across all databases.

• totalDatabases displays the total number of databases.

• totalCollections displays the total number of collections across all databases.

• totalViews displays the total number of views across all databases.

• totalIndexes displays the total number of indexes across all collections.

Monitor storage space to determine whether to manually increase the disk size.

Displays the following information:

• returned displays the average rate per second of documents returned by queries over the selected sample period.

• inserted displays the average rate per second of documents inserted over the selected sample period.

• updated displays the average rate per second of documents updated over the selected sample period.

• deleted displays the average rate per second of documents deleted over the selected sample period.

Monitor document metrics to measure the work MongoDB completes.

Displays the total consumption of memory in megabytes at a particular point in time:

• resident displays the number of megabytes of resident memory used by the mongod process. For WiredTiger deployments, this includes the WiredTiger cache plus memory used by other in-memory mongod structures. By default, mongod with WiredTiger reserves 50% of total physical memory for the cache.

• virtual displays the virtual megabytes for the mongod process. If virtual is much larger than mapped memory, the mongod process may use excessive memory for other purposes, such as connection thread stacks.

• mapped displays the number of MMAPv1 memory maps of all the data files. This number is likely similar to your total database(s) size. WiredTiger does not use memory mapped files, so this value is 0.

Monitor memory to determine whether your currrent deployment meets your memory needs.

Displays the following information:

• bytesIn displays the average rate of physical bytes (after any wire compression) sent to this database server per second over the selected sample period.

• bytesOut displays the average rate of physical bytes (after any wire compression) sent from this database server per second over the selected sample period.

• numRequests displays the average rate of requests sent to this database server per second over the selected sample period.

Monitor network metrics to track network performance.

Displays the following information:

• command displays the average rate of commands performed per second over the selected sample period.

• query displays the average rate of queries performed per second over the selected sample period.

• insert displays the average rate of inserts performed per second over the selected sample period.

• delete displays the average rate of deletes performed per second over the selected sample period.

• update displays the average rate of updates performed per second over the selected sample period.

• getmore displays the average rate of getMores performed per second on any cursor over the selected sample period. On a primary, this value can be high even if the query count is low because secondaries getMore from the primary as part of replication.

• ttldeleted displays the average rate of TTL deletes performed per second over the selected sample period. TTL deletes apply only to the primary and are replicated to secondaries.

Monitor MongoDB operations to validate performance issues related to high workloads. Confirm the type of operations responsible for the load.

Displays the following information:

• avg ms/read displays the average execution time in milliseconds per read operation over the selected sample period.

• avg ms/write displays the average execution time in milliseconds per write operation over the selected sample period.

• avg ms/write w/o flow control displays the average execution time in milliseconds per write operation over the selected sample period once the impact of flow control is subtracted from the total.

• avg ms/command displays the average execution time in milliseconds per command operation over the selected sample period.

Monitor operation execution times to identify slow operations and potential performance bottlenecks.

Displays the following information:

• rejected displays the number of operations rejected over time because they match a user-defined rejection filter. These filters prevent cluster degradation caused by inefficient queries or resource limits. You can set these filters by running the query settings command.

• killed displays the number of read operations killed over time due to exceeding the default cluster timeout. This timeout prevents unintentional long-running queries from consuming excessive database resources. Timeouts set at the operation level override the cluster-level timeout.

Monitor operation throttling to identify queries that are being rejected or killed.

Displays the average rate of page faults on this process per second over the selected sample period. In non-Windows environments this applies to hard page faults only.

Monitor page faults to determine whether to increase your memory.

Displays the following information:

• total displays the number of operations queued and waiting for any lock.

• readers displays the number of operations queued and waiting for a read lock.

• writers displays the number of operation queued and waiting for a write lock.

Monitor queues to identify potential issues and bottlenecks.

Displays the following information:

• scanned displays the average rate per second over the selected sample period of index items scanned during queries and query-plan evaluation. This rate is driven by the same value as totalKeysExamined in the output of explain().

• scanned objects displays the average rate per second over the selected sample period of documents scanned during queries and query-plan evaluation. This rate is driven by the same value as totalDocsExamined in the output of explain().

Monitor query executor to identify inefficient queries that scan more indexes or documents than necessary.

Displays the efficiency of read operations run on MongoDB:

• scanned / returned displays the ratio of the number of index items scanned to the number of documents returned by queries, since the previous data point for the selected sample period. A value of 1.0 means all returned documents exactly match the query criteria. Higher values indicate that queries scan more index items per returned document.

• scanned objects / returned displays the ratio of the number of documents scanned to the number of documents returned by queries, since the previous data point for the selected sample period.

Monitor query targeting to determine read efficiency and optimize queries and indexes.

Displays the average rate per second over the selected sample period of queries that return sorted results that cannot perform the sort operation using an index.

Monitor this metric to identify whether your queries need indexes.

Displays the amount of storage space in bytes that your stored data uses on each shard. You can access this chart only in the sharded namespace view for sharded clusters with MongoDB 6.0+.

Monitor this metric to verify whether you have balanced shards.

Displays the number of documents on each shard. You can access this chart only in the sharded namespace view for sharded clusters with MongoDB 6.0+.

Monitor this metric to verify whether you have balanced shards.

Displays the following information:

• read displays the number of read tickets available to the WiredTiger storage engine. Read tickets represent the number of concurrent read operations allowed into the storage engine. When this value reaches zero, new read requests may queue until a read ticket becomes available.

• write displays the number of write tickets available to the WiredTiger storage engine. Write tickets represent the number of concurrent write operations allowed into the storage engine. When this value reaches zero, new write requests may queue until a write ticket becomes available.

Monitor tickets available to identify storage engine concurrency constraints that may affect performance.

Displays the average object size across all collections in the database.

Monitor object size to track the size of your objects and better understand your database space.

Displays the number of collections in the database.

Monitor collections to determine restart times, continuous backup performance, and stability.

Displays the actual size of the data files in the database.

Monitor data size to ensure that database is not using too much memory or CPU.

Displays the total size of all indexes in the database. This metric includes the overhead incurred by indexes on top of the actual document data on which the indexes are based.

Monitor the index size to manage your indexes. To learn more, see Indexing Strategies.

Displays the total number of indexes in the database.

Monitor indexes to manage them. To learn more, see Indexing Strategies.

Displays the total number of contiguously allocated chunks of data file space for the database.

Monitor this metric to better understand your database space.

Displays the number of objects in the database.

Monitor this metric to better understand your database space.

Displays the storage size of the database.

Monitor storage size to determine whether to manually increase the disk size.

Displays the number of views in the database.

Monitor views to better understand your database space.

Displays the following information:

• read iops displays the read throughput of I/O operations per second for the disk partition used for MongoDB.

• write iops displays the write throughput of I/O operations per second for the disk partition used for MongoDB.

Monitor whether disk IOPS approaches the maximum provisioned IOPS. Determine whether the deployment can handle future workloads.

Displays the following information:

• read latency displays the average amount of time to read from disk.

• write latency displays the average amount of time to write to disk.

• max read latency displays the maximum Disk Read Latency value over the time period specified by the metric granularity.

• max write latency displays the maximum Disk Write Latency value over the time period specified by the metric granularity.

Monitor disk latency to track the efficiency of reading from and writing to disk.

Displays the average length of the queue of requests issued to the disk partition that stores MongoDB data.

Monitor disk queue depth to identify potential issues and bottlenecks.

Displays the following information:

• disk space free displays the total bytes of free disk space on the disk partition used by MongoDB.

• max disk space free displays the maximum Disk Space Free value over the time period specified by the metric granularity.

Monitor free disk space to determine whether to use disk auto-scaling or manually increase the disk size.

Displays the following information:

• percent disk space free displays the percent of free disk space on the partition used by MongoDB.

• max percent disk space free displays the maximum Disk Space Percent Free value over the time period specified by the metric granularity.

Monitor the percentage of free disk space to determine whether to use disk auto-scaling or manually increase the disk size.

Displays the following information:

• disk space used displays the total bytes of used disk space on the partition that runs MongoDB.

• max disk space used displays the maximum Disk Space Used value over the time period specified by the metric granularity.

Monitor the used disk space to determine whether to manually increase the disk size.

Displays the following maximum disk IOPS values over the time period specified by the metric granularity:

• max read iops maximum disk read input operations per second.

• max write iops maximum disk write input operations per second.

Monitor whether disk IOPS approaches the maximum provisioned IOPS. Determine whether the deployment can handle future workloads.

Displays the maximum disk queue depth values over the time period specified by the metric granularity. Disk queue depth is the average length of the queue of requests issued to the disk partition that stores MongoDB data.

Monitor disk queue depth to identify potential issues and bottlenecks.

Displays the maximum CPU usage values of all processes on the node, scaled to a range of 0-100% by dividing by the number of CPU cores:

• user displays the maximum Normalized System User CPU value over the time period specified by the metric granularity.

• kernel displays the maximum Normalized System Kernel CPU value over the time period specified by the metric granularity.

• nice displays the maximum Normalized System Nice CPU value over the time period specified by the metric granularity.

• iowait displays the maximum Normalized System IO Wait CPU value over the time period specified by the metric granularity.

• irq displays the maximum Normalized System IRQ CPU value over the time period specified by the metric granularity.

• softirq displays the maximum Normalized System SoftIRQ CPU value over the time period specified by the metric granularity.

• guest displays the maximum Normalized System Guest CPU value over the time period specified by the metric granularity.

• steal displays the maximum Normalized System Steal CPU value over the time period specified by the metric granularity.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

Displays the following maximum process CPU values over the time period specified by the metric granularity:

• max user displays the maximum percentage of time that the CPU spent servicing the MongoDB process.

• max kernel displays the maximum percentage of time the CPU spent servicing operating system calls for the MongoDB process.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

Displays the maximum CPU usage values of all processes on the node:

• user displays the maximum System User CPU value over the time period specified by the metric granularity.

• kernel displays the maximum System Kernel CPU value over the time period specified by the metric granularity.

• nice displays the maximum System Nice CPU value over the time period specified by the metric granularity.

• iowait displays the maximum System IO Wait CPU value over the time period specified by the metric granularity.

• irq displays the maximum System IRQ CPU value over the time period specified by the metric granularity.

• softirq displays the maximum System SoftIRQ CPU value over the time period specified by the metric granularity.

• guest displays the maximum System Guest CPU value over the time period specified by the metric granularity.

• steal displays the maximum System Steal CPU value over the time period specified by the metric granularity.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

Displays the maximum system memory values in bytes:

• used displays the maximum System Memory Used value over the time period specified by the metric granularity.

• available displays the maximum System Memory Available value over the time period specified by the metric granularity.

• free displays the maximum System Memory Free value over the time period specified by the metric granularity.

• shared displays the maximum System Memory Shared value over the time period specified by the metric granularity.

• buffers displays the maximum Buffers value over the time period specified by the metric granularity.

• cached displays the maximum Cached value over the time period specified by the metric granularity.

Monitor memory to determine whether your currrent deployment meets your memory needs.

Displays the following information:

• user displays the percentage of time that the CPU spent servicing the MongoDB process, scaled to a range of 0-100% by dividing by the number of CPU cores.

• kernel displays the percentage of time the CPU spent servicing operating system calls for the MongoDB process, scaled to a range of 0-100% by dividing by the number of CPU cores.

• max user displays the maximum Normalized Process User CPU value over the time period specified by the metric granularity.

• max kernel displays the maximum Normalized Process Kernel CPU value over the time period specified by the metric granularity.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

Displays the CPU usage of all processes on the node, scaled to a range of 0-100% by dividing by the number of CPU cores:

• user displays the percentage of time the CPU spent servicing all user applications (not just MongoDB processes), scaled to a range of 0-100% by dividing by the number of CPU cores.

• kernel displays the percentage of time the CPU spent servicing operating system calls from all processes, scaled to a range of 0-100% by dividing by the number of CPU cores.

• nice displays the percentage of time the CPU spent occupied by all processes with a positive nice value, scaled to a range of 0-100% by dividing by the number of CPU cores.

• iowait displays the percentage of time the CPU spent waiting for IO operations to complete, scaled to a range of 0-100% by dividing by the number of CPU cores.

• irq displays the percentage of time the CPU spent performing hardware interrupts, scaled to a range of 0-100% by dividing by the number of CPU cores.

• softirq displays the percentage of time the CPU spent performing software interrupts, scaled to a range of 0-100% by dividing by the number of CPU cores.

• guest displays the percentage of time the CPU spent servicing guest, which is included in user, scaled to a range of 0-100% by dividing by the number of CPU cores.

• steal displays the percentage of time the CPU had something runnable, but the hypervisor chose to run something else, scaled to a range of 0-100% by dividing by the number of CPU cores.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

Displays the following information:

• user displays the percentage of time that the CPU spent servicing the MongoDB process.

• kernel displays the percentage of time the CPU spent servicing operating system calls for the MongoDB process.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

Displays the rate at which the operating system swaps memory pages between RAM and disk:

• swapped pages in / sec shows how many pages per second the operating system reads from swap into memory.

• swapped pages out / sec shows how many pages per second the operating system writes from memory to swap.

• max swapped pages in displays the maximum Swapped Pages In value over the time period specified by the metric granularity.

• max swapped pages out displays the maximum Swapped Pages Out value over the time period specified by the metric granularity.

A high or sustained rate of swap IO can correlate with increased latency and memory pressure on the host.

Use this metric to understand how frequently the host performs swap input and output operations.

Displays the following information about swap space on the host:

• used displays the total amount of swap space currently in use.

• free displays the total amount of swap space that is still available.

• max used displays the maximum total amount of swap space in use over the selected time period.

• max free displays the maximum amount of available swap space over the selected time period.

Sustained high swap usage can indicate memory pressure on the host.

Monitor swap usage to identify when the operating system starts moving memory pages to disk.

Displays the CPU usage of all processes on the node:

• user displays the percentage of time the CPU spent servicing all user applications (not just MongoDB processes). For servers with more than 1 CPU core, this value can exceed 100%.

• kernel displays the percentage of time the CPU spent servicing operating system calls from all processes. For servers with more than 1 CPU core, this value can exceed 100%.

• nice displays the percentage of time the CPU spent occupied by all processes with a positive nice value. For servers with more than 1 CPU core, this value can exceed 100%.

• iowait displays the percentage of time the CPU spent waiting for IO operations to complete. For servers with more than 1 CPU core, this value can exceed 100%.

• irq displays the percentage of time the CPU spent performing hardware interrupts. For servers with more than 1 CPU core, this value can exceed 100%.

• softirq displays the percentage of time the CPU spent performing software interrupts. For servers with more than 1 CPU core, this value can exceed 100%.

• guest displays the percentage of time the CPU spent servicing guest, which is included in user. For servers with more than 1 CPU core, this value can exceed 100%.

• steal displays the percentage of time the CPU had something runnable, but the hypervisor chose to run something else. For servers with more than 1 CPU core, this value can exceed 100%.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

Displays the following information:

• used displays the number of bytes of physical memory in use.

• available displays an estimate of the number of bytes of system memory available for running new applications, without swapping.

• free displays the number of bytes of unused physical memory available to the system.

• shared displays the number of bytes of used shared memory shared between several processes, including RAM disks, SYS-V-IPC, and BSD-like SHMEM.

• buffers displays the number of bytes of buffer cache for temporary storage of raw disk blocks.

• cached displays the number of bytes in the page cache.

Monitor memory to determine whether your currrent deployment meets your memory needs.

Displays the following information:

• network bytes in displays the average rate of physical bytes that the network interface receives per second.

• network bytes out displays the average rate of physical bytes that the network interface transmits per second.

• max network bytes in displays the maximum network bytes in values over the time period that the metric granularity specifies.

• max network bytes out displays the maximum network bytes out values over the time period that the metric granularity specifies.

Monitor network metrics to track network performance.

CPU Usage

Displays normalized CPU usage percentage for the mongot process.

JVM Memory

Displays JVM heap memory used and maximum heap capacity for the mongot process. Use this chart to identify memory pressure that could affect search performance.

JVM GC Pause

Displays the maximum JVM garbage collection pause duration, in seconds. Frequent or long pauses can affect search query latency.

Disk Space Used

Displays the percentage of disk space used by the mongot process.

Index Size

Displays the combined size of all search indexes on the mongot process, in bytes.

Index Documents

Displays the total number of documents across all search indexes on the mongot process.

Index Segments

Displays the total number of Lucene segments across all search indexes on the mongot process.

Search Query Throughput

Displays the total rate and failed rate of Search queries, in operations per second.

Search Query Latency

Displays the average and maximum latency of Search commands, in milliseconds.

Vector Search Throughput

Displays the total rate and failed rate of Vector Search queries, in operations per second.

Vector Search Latency

Displays the average and maximum latency of Vector Search commands, in milliseconds.

Index Manager Health

Displays the number of index managers in each of the following states: STEADY_STATE, FAILED, and FAILED_EXCEEDED.