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# ZFS Adaptive Replacement Cache


<img src="https://netdata.cloud/img/filesystem.svg" width="150"/>


Plugin: proc.plugin
Module: /proc/spl/kstat/zfs/arcstats

<img src="https://img.shields.io/badge/maintained%20by-Netdata-%2300ab44" />

## Overview

This integration monitors  ZFS Adadptive Replacement Cache (ARC) statistics.



This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.


### Default Behavior

#### Auto-Detection

This integration doesn't support auto-detection.

#### Limits

The default configuration for this integration does not impose any limits on data collection.

#### Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.

## Setup


### Prerequisites

No action required.

### Configuration

#### Options



There are no configuration options.



#### via File

There is no configuration file.

##### Examples
There are no configuration examples.



## Alerts


The following alerts are available:

| Alert name  | On metric | Description |
|:------------|:----------|:------------|
| [ zfs_memory_throttle ](https://github.com/netdata/netdata/blob/master/src/health/health.d/zfs.conf) | zfs.memory_ops | number of times ZFS had to limit the ARC growth in the last 10 minutes |


## Metrics

Metrics grouped by *scope*.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.



### Per ZFS Adaptive Replacement Cache instance



This scope has no labels.

Metrics:

| Metric | Dimensions | Unit |
|:------|:----------|:----|
| zfs.arc_size | arcsz, target, min, max | MiB |
| zfs.l2_size | actual, size | MiB |
| zfs.reads | arc, demand, prefetch, metadata, l2 | reads/s |
| zfs.bytes | read, write | KiB/s |
| zfs.hits | hits, misses | percentage |
| zfs.hits_rate | hits, misses | events/s |
| zfs.dhits | hits, misses | percentage |
| zfs.dhits_rate | hits, misses | events/s |
| zfs.phits | hits, misses | percentage |
| zfs.phits_rate | hits, misses | events/s |
| zfs.mhits | hits, misses | percentage |
| zfs.mhits_rate | hits, misses | events/s |
| zfs.l2hits | hits, misses | percentage |
| zfs.l2hits_rate | hits, misses | events/s |
| zfs.list_hits | mfu, mfu_ghost, mru, mru_ghost | hits/s |
| zfs.arc_size_breakdown | recent, frequent | percentage |
| zfs.memory_ops | direct, throttled, indirect | operations/s |
| zfs.important_ops | evict_skip, deleted, mutex_miss, hash_collisions | operations/s |
| zfs.actual_hits | hits, misses | percentage |
| zfs.actual_hits_rate | hits, misses | events/s |
| zfs.demand_data_hits | hits, misses | percentage |
| zfs.demand_data_hits_rate | hits, misses | events/s |
| zfs.prefetch_data_hits | hits, misses | percentage |
| zfs.prefetch_data_hits_rate | hits, misses | events/s |
| zfs.hash_elements | current, max | elements |
| zfs.hash_chains | current, max | chains |


