# Resource usage metrics

```json metadata
{
  "title": "Resource usage metrics",
  "description": "",
  "categories": ["docs","operate","rs"],
  "tableOfContents": {"sections":[{"id":"connections","title":"Connections"},{"children":[{"id":"main-thread-cpu-usage","title":"Main thread CPU usage"},{"id":"fork-cpu-usage","title":"Fork CPU usage"},{"id":"total-cpu-usage","title":"Total CPU usage"}],"id":"cpu-usage","title":"CPU usage"},{"id":"free-disk-space","title":"Free disk space"},{"children":[{"id":"used-memory","title":"Used memory"},{"id":"free-ram","title":"Free RAM"},{"id":"memory-limit","title":"Memory limit"},{"id":"memory-usage","title":"Memory usage"}],"id":"memory","title":"Memory"},{"children":[{"id":"incoming-traffic","title":"Incoming traffic"},{"id":"outgoing-traffic","title":"Outgoing traffic"}],"id":"traffic","title":"Traffic"}]}

,
  "codeExamples": []
}
```
The following metrics are available in the Redis Software Cluster Manager UI.

## Connections

Number of connections to the database.

**Components measured**: Cluster, Node, and Database

## CPU usage

Percent of the node CPU used. 

**Components measured**:  Cluster and Node

### Main thread CPU usage 

Percent of the CPU used by the main thread.

**Components measured**: Database and Shard

### Fork CPU usage

CPU usage of Redis child forks.

**Components measured**: Database and Shard

### Total CPU usage 

Percent usage of the CPU for all nodes.

**Components measured**: Database

## Free disk space

Remaining unused disk space.

**Components measured**:  Cluster and Node

## Memory
### Used memory 

Total memory used by the database, including RAM, [Flash](https://redis.io/docs/latest/operate/rs/databases/flash) (if enabled), and [replication](https://redis.io/docs/latest/operate/rs/databases/durability-ha/replication) (if enabled).

Used memory does not include:

1. Fragmentation overhead - The ratio of memory seen by the operating system to memory allocated by Redis
2. Replication buffers at the primary nodes - Set to 10% of used memory and is between 64 MB and 2048 MB
3. Memory used by Lua scripts - Does not exceed 1 MB
4. Copy on Write (COW) operation that can be triggered by:
    - A full replication process
    - A database snapshot process
    - AOF rewrite process

Used memory is not measured during [shard migration](https://redis.io/docs/latest/operate/rs/databases/configure/replica-ha).

Additional factors for [Active-Active databases](https://redis.io/docs/latest/operate/rs/databases/active-active):

- By default, the [Active-Active replication backlog](https://redis.io/docs/latest/operate/rs/databases/active-active/manage#replication-backlog), used for synchronization between clusters or regions, is set to 1% of the database size.

- Active-Active databases have a lower threshold for activating the eviction policy, because it requires propagation to all participating clusters. The eviction policy starts to evict keys when one of the Active-Active instances reaches 80% of its memory limit.

**Components measured**: Database and Shard

### Free RAM

Available RAM for System use.

**Components measured**:  Cluster and Node

### Memory limit 

Memory size limit of the database, enforced on the [used memory](#used-memory).

**Components measured**: Database

### Memory usage 

Percent of memory used by Redis out of the [memory limit](#memory-limit).

**Components measured**: Database
## Traffic

### Incoming traffic 

Total incoming traffic to the database in bytes/sec.

All incoming traffic is not measured during [shard migration](https://redis.io/docs/latest/operate/rs/databases/configure/replica-ha).

**Components measured**: Cluster, Node and Database

#### Incoming traffic compressed

Total incoming compressed traffic (in bytes/sec) per [Active-Active](https://redis.io/docs/latest/operate/rs/databases/active-active) replica database. 

#### Incoming traffic uncompressed

Total incoming uncompressed traffic (in bytes/sec) per [Active-Active](https://redis.io/docs/latest/operate/rs/databases/active-active) replica database. 

### Outgoing traffic 

Total outgoing traffic from the database in bytes per second.

Outgoing traffic is not measured during [shard migration](https://redis.io/docs/latest/operate/rs/databases/configure/replica-ha).

**Components measured**: Cluster, Node and Database