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ARCSTAT(1) General Commands Manual ARCSTAT(1)

NAME

arcstat - report ZFS ARC and L2ARC statistics

SYNOPSIS

arcstat [-havxp] [-f field[,field]...] [-o file] [-s string] [interval [count]]

DESCRIPTION

The arcstat utility print various ZFS ARC and L2ARC statistics in vmstat-like fashion.

The arcstat command reports the following information:

c

ARC target size

dh%

Demand data hit percentage

dm%

Demand data miss percentage

mfu

MFU list hits per second

mh%

Metadata hit percentage

mm%

Metadata miss percentage

mru

MRU list hits per second

ph%

Prefetch hits percentage

pm%

Prefetch miss percentage

dhit

Demand data hits per second

dmis

Demand data misses per second

hit%

ARC hit percentage

hits

ARC reads per second

mfug

MFU ghost list hits per second

mhit

Metadata 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

pmis

Prefetch misses per second

read

Total ARC accesses per second

time

Time

size

ARC size

arcsz

Alias for size

dread

Demand data accesses per second

eskip

evict_skip per second

miss%

ARC miss percentage

mread

Metadata accesses per second

pread

Prefetch accesses per second

l2hit%

L2ARC access hit percentage

l2hits

L2ARC hits per second

l2miss

L2ARC misses per second

l2read

Total L2ARC accesses per second

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

The following options are supported:

-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:

count

Display only count reports.

interval

Specify the sampling interval in seconds.

AUTHORS

arcstat was originally written in Perl by Neelakanth Nadgir and supported only ZFS ARC statistics. Mike Harsch updated it to support L2ARC statistics. John Hixson ported it to Python for FreeNAS over some beer, after which many individuals from the OpenZFS community continued to maintain and improve it.
October 20, 2020 OpenZFS