svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
iostat(8)
iostat(8) System Administration Commands iostat(8)
NAME
iostat - report I/O statistics
SYNOPSIS
/usr/bin/iostat [-bcCdDeEiILmMnNpPrsStwxXYuz] [-l n] [-T u | d]
[disk]... [interval [count]]
DESCRIPTION
The iostat utility iteratively reports terminal, disk, and tape I/O ac‐
tivity, as well as CPU utilization. The first line of output is for all
time since boot; each subsequent line is for the prior interval only.
To compute this information, the kernel maintains a number of counters.
For each disk, the kernel counts reads, writes, bytes read, and bytes
written. The kernel also takes hi-res time stamps at queue entry and
exit points, which allows it to keep track of the residence time and
cumulative residence-length product for each queue. Using these values,
iostat produces highly accurate measures of throughput, utilization,
queue lengths, transaction rates and service time. For terminals col‐
lectively, the kernel simply counts the number of input and output
characters.
During execution of the kernel status command, the state of the system
can change. If relevant, a state change message is included in the io‐
stat output, in one of the following forms:
<<device added: sd0>>
<<device removed: sd0>>
<<partition added: sd0,a>>
<<partition removed: sd0,a>>
<<NFS mounted: nfs1>>
<<NFS unmounted: nfs1>>
<<multi-path added: ssd4>>
<<multi-path removed: ssd4>>
<<controller added: c1>>
<<controller removed: c1>>
<<processors added: 1, 3>>
<<processors removed: 1, 3>>
Note that the names printed in these state change messages are affected
by the -n and -m options as appropriate.
For more general system statistics, use sar(1), sar(8), or vmstat(8).
Output
The output of the iostat utility includes the following information.
device name of the disk
r/s reads per second
w/s writes per second
kr/s kilobytes read per second
The average I/O size during the interval can be computed from
kr/s divided by r/s.
kw/s kilobytes written per second
The average I/O size during the interval can be computed from
kw/s divided by w/s.
wait average number of transactions waiting for service (queue
length)
This is the number of I/O operations held in the device dri‐
ver queue waiting for acceptance by the device.
actv average number of transactions actively being serviced (re‐
moved from the queue but not yet completed)
This is the number of I/O operations accepted, but not yet
serviced, by the device.
svc_t average response time of transactions, in milliseconds
The svc_t output reports the overall response time, rather
than the service time, of a device. The overall time includes
the time that transactions are in queue and the time that
transactions are being serviced. The time spent in queue is
shown with the -x option in the wsvc_t output column. The
time spent servicing transactions is the true service time.
Service time is also shown with the -x option and appears in
the asvc_t output column of the same report.
%w percent of time there are transactions waiting for service
(queue non-empty)
For NFS, this is the percent of time that there is at least
one asynchronous request waiting to be started
%b percent of time the disk is busy (transactions in progress)
For NFS, this is the percent of time that there is at least
one pending NFS RPC, that is, the system is waiting for a re‐
ply from the server
wsvc_t average service time in wait queue, in milliseconds
asvc_t average service time of active transactions, in milliseconds
st percent of CPU time which was taken off by the hypervisor.
Always zero when running on physical hardware.
OPTIONS
The following options are supported:
-b Report backend statistics for virtual devices assigned to
guests such as solaris-kz(7) zones or Oracle VM Server for
SPARC guest domains. See ldm(8) manual page for definition
of the backend. It is recommended to use the option -b to‐
gether with options -x and -n.
-c Report the percentages of time the system has spent in user
mode, in system mode, time taken off by the hypervisor (see
the definition of st below), and idling. For more informa‐
tion, see the NOTES section.
-C When the -x option is also selected, report extended disk
statistics aggregated by controller id.
-d For each disk, report the number of kilobytes transferred
per second, the number of transfers per second, and the av‐
erage service time in milliseconds.
-D For each disk, report the reads per second, writes per sec‐
ond, and percentage disk utilization.
-e Display device error summary statistics. The total errors,
hard errors, soft errors, and transport errors are dis‐
played.
-E Display all device error statistics.
-N Print devchassis-path names for device only. Must be used
with -x.
-i In -E output, display the Device ID instead of the Serial
No. The Device Id is a unique identifier registered by a
driver through ddi_devid_register(9F).
-I Report the counts in each interval, rather than rates
(where applicable).
-l n Limit the number of disks included in the report to n; the
disk limit defaults to 4 for -d and -D, and unlimited for
-x. Note that disks explicitly requested (see disk below)
are not subject to this disk limit.
-L Report IO latency distribution statistics. This option can
be used to observe disk IO latency statistics with -x op‐
tion. For MPxIO enabled system(s), this option can also be
used to observe latency statistics for each path with the
-Y option. Note that the label '1us' means '1024ns' and
'1ms' means '1024*1024ns'. This option cannot be used in
conjunction with -t or -c options and will be ignored when
used with the -E option. Numbers reported in the distribu‐
tion may not add up to the exact same value as the total as
snopshots may be taken over very slightly distjoint time
periods.
-m Report file system mount points. This option is most useful
if the -P or -p option is also specified or used in con‐
junction with -Xn or -en. The -m option is useful only if
the mount point is actually listed in the output. This op‐
tion can only be used in conjunction with the -n option.
-M Display data throughput in MB/sec instead of KB/sec.
-n Display names in descriptive format. For example, cXtYdZ,
rmt/N, server:/export/path.
By default, disks are identified by instance names such as
ssd23 or md301. Combining the -n option with the -x option
causes disk names to display in the cXtYdZsN format which
is more easily associated with physical hardware character‐
istics. The cXtYdZsN format is particularly useful in Fibre
Channel (FC) environments where the FC World Wide Name ap‐
pears in the t field.
-p For each disk, report per-partition statistics in addition
to per-device statistics.
-P For each disk, report per-partition statistics only, no
per-device statistics.
-r Display data in a comma-separated format.
-s Suppress messages related to state changes.
-S Append a separator line after each iteration.
-t Report the number of characters read and written to termi‐
nals per second.
-T u | d Display a time stamp.
Specify u for a printed representation of the internal rep‐
resentation of time. See time(2). Specify d for standard
date format. See date(1).
-w Wide display format.
Using this option along with either of the options -x, -X,
-Y or their combinations will display the output in wider
format. The headers will be more descriptive and two space
gap is provided between each column in this display.
Refer the Example section for sample outputs.
-X For disks under scsi_vhci(4D) control, in addition to disk
lun statistics, also report statistics for lun.controller.
-x Report extended disk statistics. By default, disks are
identified by instance names such as ssd23 or md301. Com‐
bining the x option with the -n option causes disk names to
display in the cXtYdZsN format, more easily associated with
physical hardware characteristics. Using the cXtYdZsN for‐
mat is particularly helpful in the FibreChannel environ‐
ments where the FC World Wide Name appears in the t field.
If no output display is requested (no -x, -e, -E), -x is
implied.
-Y For disks under scsi_vhci(4D) control, in addition to disk
lun statistics, also report statistics for lun.targetport
and lun.targetport.controller.
In -n (descriptive) mode the targetport is shown in using
the target-port property of the path. Without -n the tar‐
getport is shown using the shorter port-id. All target
ports with the same target-port property value share the
same port-id. The target-port-to-port-id association does
not persist across reboot.
If no output display is requested (no -x, -e, -E), -x is
implied.
-u Print micro-second resolution for wsvc_t and asvc_t fields.
Must be used with -x.
-z Do not print lines whose underlying data values are all ze‐
ros.
The option set -xcnCXTdz interval is particularly useful for determin‐
ing whether disk I/O problems exist and for identifying problems.
OPERANDS
The following operands are supported:
count Display only count reports.
disk Disk name pattern to specify the disks to be reported. The
pattern can contain wildcard characters: *, ?, or pattern
bracket expression that starts with [. The escape character
is . See the manual page fnmatch(7) for details. In addi‐
tion to disks which names match the pattern, any active
disks up to the disk limit (see -l above) will also be re‐
ported.
interval Report once each interval seconds.
EXAMPLES
Example 1 Using iostat to Generate User and System Operation Statistics
The following command displays two reports of extended device statis‐
tics, aggregated by controller id, for user (us) and system (sy) opera‐
tions. Because the -n option is used with the -x option, devices are
identified by controller names.
example$ iostat -xcnCXTdz 5
Thursday, May 23, 2013 09:17:03 AM PDT
cpu
us sy st id
14 31 0 20
extended device statistics
r/s w/s kr/s kw wait actv wsvc_t asvc_t %w %b device
3.8 29.9 145.8 44.0 0.0 0.2 0.1 6.4 0 5 c0
666.3 814.8 12577.6 17591.1 91.3 82.3 61.6 55.6 0 2 c12
180.0 234.6 4401.1 5712.6 0.0 147.7 0.0 356.3 0 98 d10
Thursday, May 23, 2013 09:17:03 AM PDT
cpu
us sy st id
11 31 0 22
extended device statistics
r/s w/s kr/s kw wait actv wsvc_t asvc_t %w %b device
0.8 41.0 5.2 20.5 0.0 0.2 0.2 4.4 0 6 c0
565.3 581.7 8573.2 10458.9 0.0 26.6 0.0 23.2 0 3 c12
106.5 81.3 3393.2 1948.6 0.0 5.7 0.0 30.1 0 99 d10
Example 2 Using iostat to Generate TTY Statistics
The following command displays two reports on the activity of five
disks in different modes of operation. Because the -x option is used,
disks are identified by instance names.
example$ iostat -xt 5 2
extended device statistics tty
device r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b tin tout
blkdev0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 0 1
sd0 0.1 19.3 1.4 92.4 0.0 0.0 0.2 1.6 0 1
sd1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
nfs9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0 0
nfs10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7.6 0 0
nfs11 0.0 0.0 0.0 0.0 0.0 0.0 0.0 15.6 0 0
nfs12 0.3 0.0 1.9 0.0 0.0 0.0 0.0 30.5 0 1
extended device statistics tty
device r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b tin tout
blkdev0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 0 132
sd0 0.0 30.8 0.0 345.6 0.0 0.1 0.0 2.1 0 1
sd1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
nfs9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
nfs10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
nfs11 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
nfs12 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
Example 3 Using iostat to Generate Partition and Device Statistics
The following command generates partition and device statistics for
each disk. Because the -n option is used with the -x option, disks are
identified by controller names.
example$ iostat -xnp
extended device statistics
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
0.4 0.3 10.4 7.9 0.0 0.0 0.0 36.9 0 1 c0t0d0
0.3 0.3 9.0 7.3 0.0 0.0 0.0 37.2 0 1 c0t0d0s0
0.0 0.0 0.1 0.5 0.0 0.0 0.0 34.0 0 0 c0t0d0s1
0.0 0.0 0.0 0.1 0.0 0.0 0.6 35.0 0 0 fuji:/export/home/user3
Example 4 Show Translation from Instance Name to Descriptive Name
The following example illustrates the use of iostat to translate a spe‐
cific instance name to a descriptive name.
example$ iostat -xn sd1
extended device statistics
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c8t1d0
Example 5 Show Target Port and Controller Activity for a Specific Disk
In the following example, there are four controllers, all connected to
the same target port.
# iostat -Y ssd6
extended device statistics
device r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b
ssd6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 12.7 0 0
ssd6.t2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
ssd6.t2.fp4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
ssd6.t4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
ssd6.t4.fp1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0
Example 6 Using iostat to Generate disk IO Latency Distribution
The following command generates path latency distribution statistics
for the specified disk.
example$ iostat -Lx sd1
extended device statistics
device r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b
sd1 14.4 16.5 426.7 758.2 0.0 0.4 0.1 13.6 0 11
latency range count density distribution
<32us 0 0.00% 0.00%
32-64us 696 0.87% 0.87%
64-128us 1622 2.03% 2.90%
128-256us 5609 7.01% 9.90%
256-512us 2655 3.32% 13.22%
512-1024us 4745 5.93% 19.15%
1-2ms 4463 5.58% 24.73%
2-4ms 7159 8.94% 33.67%
4-8ms 16899 21.11% 54.78%
8-16ms 14824 18.52% 73.30%
16-32ms 12630 15.78% 89.08%
32-64ms 6491 8.11% 97.19%
64-128ms 1908 2.38% 99.58%
128-256ms 301 0.38% 99.95%
256-512ms 38 0.05% 100.00%
>1024ms 0 0.00% 100.00%
total 80040
Example 7 iostat wide display sample-1
example$ iostat -xw sd1
extended device statistics
Device Reads/s Writes/s Read KB/s Written KB/s WaitQ SvcQ AvSvcTimeInWaitQ AvSvcTimeActTrans %Wait %Busy
sd1 0.7 33.0 19.6 239.6 0.0 0.0 0.0 0.2 0 0
Example 8 iostat wide display sample-2
example$ iostat -Yw sd1
extended device statistics
Device Reads/s Writes/s Read KB/s Written KB/s WaitQ SvcQ AvSvcTimeInWaitQ AvSvcTimeActTrans %Wait %Busy
sd1 0.7 33.0 19.6 239.8 0.0 0.0 0.0 0.2 0 0
sd1.t9 0.7 33.0 40.4 263.2 0.0 0.0 0.0 0.2 0 0
sd1.t9.lmrc1 0.7 33.0 40.4 263.2 0.0 0.0 0.0 0.2 0 0
Example 9 iostat wide display sample-3
example$ iostat -IxnwCX sd1
extended device statistics
Reads/i Writes/i Read KB/i Written KB/i WaitQ SvcQ AvSvcTimeInWaitQ AvSvcTimeActTrans %Wait %Busy Device
37124.0 1911845.0 1116521.1 13937283.0 0.0 0.0 0.0 0.2 0 0 c0
37124.0 1911845.0 1116521.1 13937283.0 0.0 0.0 0.0 0.2 0 0 c0t1d0
38413.0 1911778.0 2302469.1 15273619.0 0.0 0.0 0.0 0.2 0 0 c0t1d0.c1
Example 10 Showing backend statistics for virtual devices
The following example demonstrates how to show extended backend statis‐
tics using descriptive names and how to filter results using a pattern.
The report contains disks which names match the pattern kz*. In the
output one can see disks assigned to solaris-kz(7) zones named kz1 and
kz2.
example$ iostat -xnb 'kz*' 1 1
extended device statistics
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
3.0 4.5 64.8 93.9 0.0 0.0 3.4 5.2 1 1 kz1/disk0
0.2 0.0 0.1 0.0 0.0 0.0 0.0 5.2 0 0 kz1/disk1
30.8 31.9 671.5 881.9 0.1 0.2 1.4 2.7 3 9 kz2/disk0
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ Availabilitysystem/core-os _ Interface StabilitySee be‐
low.
Invocation is evolving. Human readable output is unstable.
SEE ALSO
date(1), sar(1), time(2), scsi_vhci(4D), attributes(7), mpstat(8),
sar(8), vmstat(8)
NOTES
The sum of CPU utilization might vary slightly from 100 because of
rounding errors in the production of a percentage figure.
The svc_t response time is not particularly significant when the I/0
(r/s+w/s) rates are under 0.5 per second. Harmless spikes are fairly
normal in such cases.
The mpstat utility reports the same st, usr, and sys statistics. For
more information, see the mpstat(8) man page.
When executed in a zone and if the pools facility is active, iostat
will only provide information for those processors in the processor set
of the pool to which the zone is bound.
For NFS, %w indicates asynchronous activity such as read-ahead or
write-behind. These requests are typically processed in parallel with
application I/Os. A large value does not necessarily indicate a perfor‐
mance problem.
HISTORY
The -b option and the ability to use wildcard characters to specify
disks were added in Oracle Solaris 11.4.78.
The -N and -S options were added in Oracle Solaris 11.4.60.
The -w option was added in Oracle Solaris 11.4.33.
The -u option was added in Oracle Solaris 11.4.16.
The -L option was added in Oracle Solaris 11.4.0.
The -Y option was added in Solaris 10 8/07 (Update 4).
The -X option was added in Solaris 9.
The -C, -m, -r, -s, -T, and -z options were added in Solaris 8.
The -E, -e, -M, -n, -P, and -p options were added in Solaris 2.6.
The -x option was added in Solaris 2.0.
The iostat command, including support for the -c, -D, -d, -I, and -t
options, has been included in all Sun and Oracle releases of Solaris.
Oracle Solaris 11.4 17 Jul 2025 iostat(8)