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. \"
. \" 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.
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. \" Copyright (c) 2020 by AJ Jordan. All rights reserved.
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. \"
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.TH ARCSTAT 1 "May 7, 2020"
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.SH NAME
arcstat \- report ZFS ARC and L2ARC statistics
.SH SYNOPSIS
.LP
.nf
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\fB arcstat\fR [\fB -hvx\fR ] [\fB -f field[,field]...\fR ] [\fB -o file\fR ] [\fB -s string\fR ] [\fB interval\fR [\fB count\fR ]]
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.fi
.SH DESCRIPTION
.LP
The \fB arcstat\fR utility print various ZFS ARC and L2ARC statistics in
vmstat-like fashion.
.sp
.sp
.LP
The \fB arcstat\fR command reports the following information:
.sp
.ne 2
. \"
.sp
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.ne 1
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.na
\fB c \fR
.ad
.RS 14 n
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ARC target size
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.RE
.sp
.ne 2
.na
\fB dh% \fR
.ad
.RS 14 n
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Demand data hit percentage
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.RE
.sp
.ne 2
.na
\fB dm% \fR
.ad
.RS 14 n
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Demand data miss percentage
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.RE
.sp
.ne 2
.na
\fB mfu \fR
.ad
.RS 14 n
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MFU list hits per second
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.RE
.sp
.ne 2
.na
\fB mh% \fR
.ad
.RS 14 n
Metadata hit percentage
.RE
.sp
.ne 2
.na
\fB mm% \fR
.ad
.RS 14 n
Metadata miss percentage
.RE
.sp
.ne 2
.na
\fB mru \fR
.ad
.RS 14 n
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MRU list hits per second
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.RE
.sp
.ne 2
.na
\fB ph% \fR
.ad
.RS 14 n
Prefetch hits percentage
.RE
.sp
.ne 2
.na
\fB pm% \fR
.ad
.RS 14 n
Prefetch miss percentage
.RE
.sp
.ne 2
.na
\fB dhit \fR
.ad
.RS 14 n
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Demand data hits per second
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.RE
.sp
.ne 2
.na
\fB dmis \fR
.ad
.RS 14 n
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Demand data misses per second
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.RE
.sp
.ne 2
.na
\fB hit% \fR
.ad
.RS 14 n
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ARC hit percentage
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.RE
.sp
.ne 2
.na
\fB hits \fR
.ad
.RS 14 n
ARC reads per second
.RE
.sp
.ne 2
.na
\fB mfug \fR
.ad
.RS 14 n
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MFU ghost list hits per second
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.RE
.sp
.ne 2
.na
\fB mhit \fR
.ad
.RS 14 n
Metadata hits per second
.RE
.sp
.ne 2
.na
\fB miss \fR
.ad
.RS 14 n
ARC misses per second
.RE
.sp
.ne 2
.na
\fB mmis \fR
.ad
.RS 14 n
Metadata misses per second
.RE
.sp
.ne 2
.na
\fB mrug \fR
.ad
.RS 14 n
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MRU ghost list hits per second
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.RE
.sp
.ne 2
.na
\fB phit \fR
.ad
.RS 14 n
Prefetch hits per second
.RE
.sp
.ne 2
.na
\fB pmis \fR
.ad
.RS 14 n
Prefetch misses per second
.RE
.sp
.ne 2
.na
\fB read \fR
.ad
.RS 14 n
Total ARC accesses per second
.RE
.sp
.ne 2
.na
\fB time \fR
.ad
.RS 14 n
Time
.RE
.sp
.ne 2
.na
\fB arcsz \fR
.ad
.RS 14 n
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ARC size
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.RE
.sp
.ne 2
.na
\fB dread \fR
.ad
.RS 14 n
Demand data accesses per second
.RE
.sp
.ne 2
.na
\fB eskip \fR
.ad
.RS 14 n
evict_skip per second
.RE
.sp
.ne 2
.na
\fB miss% \fR
.ad
.RS 14 n
ARC miss percentage
.RE
.sp
.ne 2
.na
\fB mread \fR
.ad
.RS 14 n
Metadata accesses per second
.RE
.sp
.ne 2
.na
\fB pread \fR
.ad
.RS 14 n
Prefetch accesses per second
.RE
.sp
.ne 2
.na
\fB l2hit% \fR
.ad
.RS 14 n
L2ARC access hit percentage
.RE
.sp
.ne 2
.na
\fB l2hits \fR
.ad
.RS 14 n
L2ARC hits per second
.RE
.sp
.ne 2
.na
\fB l2miss \fR
.ad
.RS 14 n
L2ARC misses per second
.RE
.sp
.ne 2
.na
\fB l2read \fR
.ad
.RS 14 n
Total L2ARC accesses per second
.RE
.sp
.ne 2
.na
\fB l2size \fR
.ad
.RS 14 n
Size of the L2ARC
.RE
.sp
.ne 2
.na
\fB mtxmis \fR
.ad
.RS 14 n
mutex_miss per second
.RE
.sp
.ne 2
.na
\fB l2bytes \fR
.ad
.RS 14 n
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Bytes read per second from the L2ARC
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.RE
.sp
.ne 2
.na
\fB l2miss% \fR
.ad
.RS 14 n
L2ARC access miss percentage
.RE
.sp
.ne 2
.na
\fB l2asize \fR
.ad
.RS 14 n
Actual (compressed) size of the L2ARC
.RE
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.sp
.ne 2
.na
\fB grow \fR
.ad
.RS 14 n
ARC grow disabled
.RE
.sp
.ne 2
.na
\fB need \fR
.ad
.RS 14 n
ARC reclaim needed
.RE
.sp
.ne 2
.na
\fB free \fR
.ad
.RS 14 n
ARC free memory
.RE
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. \"
.SH OPTIONS
.LP
The following options are supported:
.sp
.ne 2
.na
\fB \fB -f\fR \fR
.ad
.RS 12 n
Display only specific fields. See \fB DESCRIPTION\fR for supported statistics.
.RE
.sp
.ne 2
.na
\fB \fB -h\fR \fR
.ad
.RS 12 n
Display help message.
.RE
.sp
.ne 2
.na
\fB \fB -o\fR \fR
.ad
.RS 12 n
Report statistics to a file instead of the standard output.
.RE
.sp
.ne 2
.na
\fB \fB -s\fR \fR
.ad
.RS 12 n
Display data with a specified separator (default: 2 spaces).
.RE
.sp
.ne 2
.na
\fB \fB -x\fR \fR
.ad
.RS 12 n
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 12 n
Show field headers and definitions
.RE
.SH OPERANDS
.LP
The following operands are supported:
.sp
.ne 2
.na
\fB \fI count\fR \fR
.ad
.RS 12 n
Display only \fI count\fR reports.
.RE
.sp
.ne 2
.na
\fB \fI interval\fR \fR
.ad
.RS 12 n
Specify the sampling interval in seconds.
.RE
.SH AUTHORS
.LP
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arcstat was originally written in Perl by Neelakanth Nadgir and supported only ZFS ARC statistics.
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Mike Harsch updated it to support L2ARC statistics.
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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.