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.
