.\"
.\" This file and its contents are supplied under the terms of the
.\" Common Development and Distribution License ("CDDL"), version 1.0.
.\" You may only use this file in accordance with the terms of version
.\" 1.0 of the CDDL.
.\"
.\" A full copy of the text of the CDDL should have accompanied this
.\" source.  A copy of the CDDL is also available via the Internet at
.\" http://www.illumos.org/license/CDDL.
.\"
.\"
.\" Copyright 2014 Adam Stevko.  All rights reserved.
.\" Copyright (c) 2015 by Delphix. All rights reserved.
.\" Copyright (c) 2020 by AJ Jordan. All rights reserved.
.\"
.TH ARCSTAT 8 "Oct 20, 2020" OpenZFS
.SH NAME
arcstat \- report ZFS ARC and L2ARC statistics
.SH SYNOPSIS
.LP
.nf
\fBarcstat\fR [\fB-havxp\fR] [\fB-f field[,field]...\fR] [\fB-o file\fR] [\fB-s string\fR] [\fBinterval\fR [\fBcount\fR]]
.fi

.SH DESCRIPTION
.LP
The \fBarcstat\fR utility print various ZFS ARC and L2ARC statistics in
vmstat-like fashion.
.sp

.sp
.LP
The \fBarcstat\fR command reports the following information:
.sp
.ne 2

.\"
.sp
.ne 1
.na
\fBc \fR
.ad
.RS 14n
ARC target size
.RE

.sp
.ne 2
.na
\fBdh% \fR
.ad
.RS 14n
Demand data hit percentage
.RE

.sp
.ne 2
.na
\fBdm% \fR
.ad
.RS 14n
Demand data miss percentage
.RE

.sp
.ne 2
.na
\fBmfu \fR
.ad
.RS 14n
MFU list hits per second
.RE

.sp
.ne 2
.na
\fBmh% \fR
.ad
.RS 14n
Metadata hit percentage
.RE

.sp
.ne 2
.na
\fBmm% \fR
.ad
.RS 14n
Metadata miss percentage
.RE

.sp
.ne 2
.na
\fBmru \fR
.ad
.RS 14n
MRU list hits per second
.RE

.sp
.ne 2
.na
\fBph% \fR
.ad
.RS 14n
Prefetch hits percentage
.RE

.sp
.ne 2
.na
\fBpm% \fR
.ad
.RS 14n
Prefetch miss percentage
.RE

.sp
.ne 2
.na
\fBdhit \fR
.ad
.RS 14n
Demand data hits per second
.RE

.sp
.ne 2
.na
\fBdmis \fR
.ad
.RS 14n
Demand data misses per second
.RE

.sp
.ne 2
.na
\fBhit% \fR
.ad
.RS 14n
ARC hit percentage
.RE

.sp
.ne 2
.na
\fBhits \fR
.ad
.RS 14n
ARC reads per second
.RE

.sp
.ne 2
.na
\fBmfug \fR
.ad
.RS 14n
MFU ghost list hits per second
.RE

.sp
.ne 2
.na
\fBmhit \fR
.ad
.RS 14n
Metadata hits per second
.RE

.sp
.ne 2
.na
\fBmiss \fR
.ad
.RS 14n
ARC misses per second
.RE

.sp
.ne 2
.na
\fBmmis \fR
.ad
.RS 14n
Metadata misses per second
.RE

.sp
.ne 2
.na
\fBmrug \fR
.ad
.RS 14n
MRU ghost list hits per second
.RE

.sp
.ne 2
.na
\fBphit \fR
.ad
.RS 14n
Prefetch hits per second
.RE

.sp
.ne 2
.na
\fBpmis \fR
.ad
.RS 14n
Prefetch misses per second
.RE

.sp
.ne 2
.na
\fBread \fR
.ad
.RS 14n
Total ARC accesses per second
.RE

.sp
.ne 2
.na
\fBtime \fR
.ad
.RS 14n
Time
.RE

.sp
.ne 2
.na
\fBsize \fR
.ad
.RS 14n
ARC size
.RE

.sp
.ne 2
.na
\fBarcsz \fR
.ad
.RS 14n
Alias for \fBsize\fR
.RE

.sp
.ne 2
.na
\fBdread \fR
.ad
.RS 14n
Demand data accesses per second
.RE

.sp
.ne 2
.na
\fBeskip \fR
.ad
.RS 14n
evict_skip per second
.RE

.sp
.ne 2
.na
\fBmiss% \fR
.ad
.RS 14n
ARC miss percentage
.RE

.sp
.ne 2
.na
\fBmread \fR
.ad
.RS 14n
Metadata accesses per second
.RE

.sp
.ne 2
.na
\fBpread \fR
.ad
.RS 14n
Prefetch accesses per second
.RE

.sp
.ne 2
.na
\fBl2hit% \fR
.ad
.RS 14n
L2ARC access hit percentage
.RE

.sp
.ne 2
.na
\fBl2hits \fR
.ad
.RS 14n
L2ARC hits per second
.RE

.sp
.ne 2
.na
\fBl2miss \fR
.ad
.RS 14n
L2ARC misses per second
.RE

.sp
.ne 2
.na
\fBl2read \fR
.ad
.RS 14n
Total L2ARC accesses per second
.RE

.sp
.ne 2
.na
\fBl2size \fR
.ad
.RS 14n
Size of the L2ARC
.RE

.sp
.ne 2
.na
\fBmtxmis \fR
.ad
.RS 14n
mutex_miss per second
.RE

.sp
.ne 2
.na
\fBl2bytes \fR
.ad
.RS 14n
Bytes read per second from the L2ARC
.RE

.sp
.ne 2
.na
\fBl2miss% \fR
.ad
.RS 14n
L2ARC access miss percentage
.RE

.sp
.ne 2
.na
\fBl2asize \fR
.ad
.RS 14n
Actual (compressed) size of the L2ARC
.RE

.sp
.ne 2
.na
\fBgrow \fR
.ad
.RS 14n
ARC grow disabled
.RE

.sp
.ne 2
.na
\fBneed \fR
.ad
.RS 14n
ARC reclaim needed
.RE

.sp
.ne 2
.na
\fBfree \fR
.ad
.RS 14n
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 \fBavail\fR above zero, \fBavail\fR is usually more instructive to observe than \fBfree\fR.
.RE

.sp
.ne 2
.na
\fBavail \fR
.ad
.RS 14n
The ARC's idea of how much free memory is available to it, which is a bit less than \fBfree\fR.
May temporarily be negative, in which case the ARC will reduce the target size \fBc\fR.
.RE
.\"

.SH OPTIONS
.LP
The following options are supported:

.sp
.ne 2
.na
\fB\fB-a\fR\fR
.ad
.RS 12n
Print all possible stats.
.RE

.sp
.ne 2
.na
\fB\fB-f\fR\fR
.ad
.RS 12n
Display only specific fields. See \fBDESCRIPTION\fR for supported statistics.
.RE

.sp
.ne 2
.na
\fB\fB-h\fR\fR
.ad
.RS 12n
Display help message.
.RE

.sp
.ne 2
.na
\fB\fB-o\fR\fR
.ad
.RS 12n
Report statistics to a file instead of the standard output.
.RE

.sp
.ne 2
.na
\fB\fB-p\fR\fR
.ad
.RS 12n
Disable auto-scaling of numerical fields (for raw, machine-parsable values).
.RE

.sp
.ne 2
.na
\fB\fB-s\fR\fR
.ad
.RS 12n
Display data with a specified separator (default: 2 spaces).
.RE

.sp
.ne 2
.na
\fB\fB-x\fR\fR
.ad
.RS 12n
Print extended stats (same as -f time,mfu,mru,mfug,mrug,eskip,mtxmis,dread,pread,read).
.RE

.sp
.ne 2
.na
\fB\fB-v\fR\fR
.ad
.RS 12n
Show field headers and definitions
.RE

.SH OPERANDS
.LP
The following operands are supported:
.sp
.ne 2
.na
\fB\fIcount\fR\fR
.ad
.RS 12n
Display only \fIcount\fR reports.
.RE

.sp
.ne 2
.na
\fB\fIinterval\fR\fR
.ad
.RS 12n
Specify the sampling interval in seconds.
.RE

.SH AUTHORS
.LP
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.