---
name: "arcstat"
section: "8"
platform: "linux"
package: "zfsutils-linux"
version: "2.3.9-0+deb13u1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/arcstat/8"
---

# arcstat(8)

report ZFS ARC and L2ARC statistics

## NAME

**arcstat** – report ZFS ARC and L2ARC statistics

## SYNOPSIS

**arcstat** \[**-havxp**\] \[**-f** *field*\[,*field*…\]\] \[**-o** *file*\] \[**-s** *string*\] \[*interval*\] \[*count*\]

## DESCRIPTION

**arcstat** prints various ZFS ARC and L2ARC statistics in vmstat-like fashion:

- **c**

  ARC target size

- **dh%**

  Demand hit percentage

- **di%**

  Demand I/O hit percentage

- **dm%**

  Demand miss percentage

- **ddh%**

  Demand data hit percentage

- **ddi%**

  Demand data I/O hit percentage

- **ddm%**

  Demand data miss percentage

- **dmh%**

  Demand metadata hit percentage

- **dmi%**

  Demand metadata I/O hit percentage

- **dmm%**

  Demand metadata miss percentage

- **mfu**

  MFU list hits per second

- **mh%**

  Metadata hit percentage

- **mi%**

  Metadata I/O hit percentage

- **mm%**

  Metadata miss percentage

- **mru**

  MRU list hits per second

- **ph%**

  Prefetch hits percentage

- **pi%**

  Prefetch I/O hits percentage

- **pm%**

  Prefetch miss percentage

- **pdh%**

  Prefetch data hits percentage

- **pdi%**

  Prefetch data I/O hits percentage

- **pdm%**

  Prefetch data miss percentage

- **pmh%**

  Prefetch metadata hits percentage

- **pmi%**

  Prefetch metadata I/O hits percentage

- **pmm%**

  Prefetch metadata miss percentage

- **dhit**

  Demand hits per second

- **dioh**

  Demand I/O hits per second

- **dmis**

  Demand misses per second

- **ddhit**

  Demand data hits per second

- **ddioh**

  Demand data I/O hits per second

- **ddmis**

  Demand data misses per second

- **dmhit**

  Demand metadata hits per second

- **dmioh**

  Demand metadata I/O hits per second

- **dmmis**

  Demand metadata misses per second

- **hit%**

  ARC hit percentage

- **hits**

  ARC hits per second

- **ioh%**

  ARC I/O hits percentage

- **iohs**

  ARC I/O hits per second

- **mfug**

  MFU ghost list hits per second

- **mhit**

  Metadata hits per second

- **mioh**

  Metadata I/O hits per second

- **miss**

  ARC misses per second

- **mmis**

  Metadata misses per second

- **mrug**

  MRU ghost list hits per second

- **phit**

  Prefetch hits per second

- **pioh**

  Prefetch I/O hits per second

- **pmis**

  Prefetch misses per second

- **pdhit**

  Prefetch data hits per second

- **pdioh**

  Prefetch data I/O hits per second

- **pdmis**

  Prefetch data misses per second

- **pmhit**

  Prefetch metadata hits per second

- **pmioh**

  Prefetch metadata I/O hits per second

- **pmmis**

  Prefetch metadata misses per second

- **read**

  Total ARC accesses per second

- **time**

  Current time

- **size**

  ARC size

- **arcsz**

  Alias for **size**

- **unc**

  Uncached list hits per second

- **dread**

  Demand accesses per second

- **ddread**

  Demand data accesses per second

- **dmread**

  Demand metadata accesses per second

- **eskip**

  evict\_skip per second

- **miss%**

  ARC miss percentage

- **mread**

  Metadata accesses per second

- **pread**

  Prefetch accesses per second

- **pdread**

  Prefetch data accesses per second

- **pmread**

  Prefetch metadata accesses per second

- **l2hit%**

  L2ARC access hit percentage

- **l2hits**

  L2ARC hits per second

- **l2miss**

  L2ARC misses per second

- **l2read**

  Total L2ARC accesses per second

- **l2pref**

  L2ARC prefetch allocated size per second

- **l2pref%**

  L2ARC prefetch allocated size percentage

- **l2mfu**

  L2ARC MFU allocated size per second

- **l2mfu%**

  L2ARC MFU allocated size percentage

- **l2mru**

  L2ARC MRU allocated size per second

- **l2mru%**

  L2ARC MRU allocated size percentage

- **l2data**

  L2ARC data (buf content) allocated size per second

- **l2data%**

  L2ARC data (buf content) allocated size percentage

- **l2meta**

  L2ARC metadata (buf content) allocated size per second

- **l2meta%**

  L2ARC metadata (buf content) allocated size percentage

- **l2size**

  Size of the L2ARC

- **mtxmis**

  mutex\_miss per second

- **l2bytes**

  Bytes read per second from the L2ARC

- **l2miss%**

  L2ARC access miss percentage

- **l2asize**

  Actual (compressed) size of the L2ARC

- **grow**

  ARC grow disabled

- **need**

  ARC reclaim needed

- **free**

  The ARC's idea of how much free memory there is, which includes evictable memory in the page cache. Since the ARC tries to keep **avail** above zero, **avail** is usually more instructive to observe than **free**.

- **avail**

  The ARC's idea of how much free memory is available to it, which is a bit less than **free**. May temporarily be negative, in which case the ARC will reduce the target size **c**.

## OPTIONS

- **-a**

  Print all possible stats.

- **-f**

  Display only specific fields. See DESCRIPTION for supported statistics.

- **-h**

  Display help message.

- **-o**

  Report statistics to a file instead of the standard output.

- **-p**

  Disable auto-scaling of numerical fields (for raw, machine-parsable values).

- **-s**

  Display data with a specified separator (default: 2 spaces).

- **-x**

  Print extended stats (same as **-f** **time**,**mfu**,**mru**,**mfug**,**mrug**,**eskip**,**mtxmis**,**dread**,**pread**,**read**).

- **-v**

  Show field headers and definitions

## OPERANDS

The following operands are supported:

- *interval*

  Specify the sampling interval in seconds.

- *count*

  Display only *count* reports.