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All rights reserved. .\" .TH IOSTAT 1M "Mar 23, 2009" .SH NAME iostat \- report I/O statistics .SH SYNOPSIS .LP .nf \fB/usr/bin/iostat\fR [\fB-cCdDeEiImMnpPrstxXYz\fR] [\fB-l\fR \fIn\fR] [\fB-T\fR u | d] [\fIdisk\fR]... [\fIinterval\fR [\fIcount\fR]] .fi .SH DESCRIPTION .sp .LP The \fBiostat\fR utility iteratively reports terminal, disk, and tape \fBI/O\fR activity, as well as \fBCPU\fR utilization. The first line of output is for all time since boot; each subsequent line is for the prior interval only. .sp .LP 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, \fBiostat\fR produces highly accurate measures of throughput, utilization, queue lengths, transaction rates and service time. For terminals collectively, the kernel simply counts the number of input and output characters. .sp .LP During execution of the kernel status command, the \fBstate\fR of the system can change. If relevant, a state change message is included in the \fBiostat\fR output, in one of the following forms: .sp .in +2 .nf <<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>> .fi .in -2 .sp .sp .LP Note that the \fBnames\fR printed in these state change messages are affected by the \fB-n\fR and \fB-m\fR options as appropriate. .sp .LP For more general system statistics, use \fBsar\fR(1), \fBsar\fR(1M), or \fBvmstat\fR(1M). .SS "Output" .sp .LP The output of the \fBiostat\fR utility includes the following information. .sp .ne 2 .na \fB\fBdevice\fR\fR .ad .RS 10n name of the disk .RE .sp .ne 2 .na \fB\fBr/s\fR\fR .ad .RS 10n reads per second .RE .sp .ne 2 .na \fB\fBw/s\fR\fR .ad .RS 10n writes per second .RE .sp .ne 2 .na \fB\fBkr/s\fR\fR .ad .RS 10n kilobytes read per second .sp The average I/O size during the interval can be computed from \fBkr/s\fR divided by \fBr/s\fR. .RE .sp .ne 2 .na \fB\fBkw/s\fR\fR .ad .RS 10n kilobytes written per second .sp The average I/O size during the interval can be computed from \fBkw/s\fR divided by \fBw/s\fR. .RE .sp .ne 2 .na \fB\fBwait\fR\fR .ad .RS 10n average number of transactions waiting for service (queue length) .sp This is the number of I/O operations held in the device driver queue waiting for acceptance by the device. .RE .sp .ne 2 .na \fB\fBactv\fR\fR .ad .RS 10n average number of transactions actively being serviced (removed from the queue but not yet completed) .sp This is the number of I/O operations accepted, but not yet serviced, by the device. .RE .sp .ne 2 .na \fB\fBsvc_t\fR\fR .ad .RS 10n average response time of transactions, in milliseconds .sp The \fBsvc_t\fR output reports the overall \fBresponse\fR time, rather than the \fBservice\fR 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 \fB-x\fR option in the \fBwsvc_t\fR output column. The time spent servicing transactions is the true service time. Service time is also shown with the \fB-x\fR option and appears in the \fBasvc_t\fR output column of the same report. .RE .sp .ne 2 .na \fB\fB%w\fR\fR .ad .RS 10n percent of time there are transactions waiting for service (queue non-empty) .RE .sp .ne 2 .na \fB\fB%b\fR\fR .ad .RS 10n percent of time the disk is busy (transactions in progress) .RE .sp .ne 2 .na \fB\fBwsvc_t\fR\fR .ad .RS 10n average service time in wait queue, in milliseconds .RE .sp .ne 2 .na \fB\fBasvc_t\fR\fR .ad .RS 10n average service time of active transactions, in milliseconds .RE .SH OPTIONS .sp .LP The following options are supported: .sp .ne 2 .na \fB\fB-c\fR\fR .ad .RS 12n Report the percentage of time the system has spent in user mode, in system mode, in dtrace probes, and idling. See the NOTES section and \fBmpstat\fR(1m) for more information. .RE .sp .ne 2 .na \fB\fB-C\fR\fR .ad .RS 12n When the \fB-x\fR option is also selected, report extended disk statistics aggregated by \fIcontroller id\fR. .RE .sp .ne 2 .na \fB\fB-d\fR\fR .ad .RS 12n For each disk, report the number of kilobytes transferred per second, the number of transfers per second, and the average service time in milliseconds. .RE .sp .ne 2 .na \fB\fB-D\fR\fR .ad .RS 12n For each disk, report the reads per second, writes per second, and percentage disk utilization. .RE .sp .ne 2 .na \fB\fB-e\fR\fR .ad .RS 12n Display device error summary statistics. The total errors, hard errors, soft errors, and transport errors are displayed. .RE .sp .ne 2 .na \fB\fB-E\fR\fR .ad .RS 12n Display all device error statistics. .RE .sp .ne 2 .na \fB\fB-i\fR\fR .ad .RS 12n In \fB-E\fR output, display the \fBDevice ID\fR instead of the \fBSerial No\fR. The \fBDevice Id\fR is a unique identifier registered by a driver through \fBddi_devid_register\fR(9F). .RE .sp .ne 2 .na \fB\fB-I\fR\fR .ad .RS 12n Report the counts in each interval, rather than rates (where applicable). .RE .sp .ne 2 .na \fB\fB-l\fR \fIn\fR\fR .ad .RS 12n Limit the number of disks included in the report to \fIn\fR; the disk limit defaults to 4 for \fB-d\fR and \fB-D\fR, and unlimited for \fB-x\fR. Note: disks explicitly requested (see \fIdisk\fR below) are not subject to this disk limit. .RE .sp .ne 2 .na \fB\fB-m\fR\fR .ad .RS 12n Report file system mount points. This option is most useful if the \fB-P\fR or \fB-p\fR option is also specified or used in conjunction with \fB-Xn\fR or \fB-en\fR. The \fB-m\fR option is useful only if the mount point is actually listed in the output. This option can only be used in conjunction with the \fB-n\fR option. .RE .sp .ne 2 .na \fB\fB-M\fR\fR .ad .RS 12n Display data throughput in \fBMB\fR/sec instead of KB/sec. .RE .sp .ne 2 .na \fB\fB-n\fR\fR .ad .RS 12n Display names in descriptive format. For example, \fBcXtYdZ\fR, \fBrmt/N\fR, \fBserver:/export/path\fR. .sp By default, disks are identified by instance names such as \fBssd23\fR or \fBmd301\fR. Combining the \fB-n\fR option with the \fB-x\fR option causes disk names to display in the \fBcXtYdZsN\fR format which is more easily associated with physical hardware characteristics. The \fBcXtYdZsN\fR format is particularly useful in FibreChannel (FC) environments where the FC World Wide Name appears in the \fBt\fR field. .RE .sp .ne 2 .na \fB\fB-p\fR\fR .ad .RS 12n For each disk, report per-partition statistics in addition to per-device statistics. .RE .sp .ne 2 .na \fB\fB-P\fR\fR .ad .RS 12n For each disk, report per-partition statistics only, no per-device statistics. .RE .sp .ne 2 .na \fB\fB-r\fR\fR .ad .RS 12n Display data in a comma-separated format. .RE .sp .ne 2 .na \fB\fB-s\fR\fR .ad .RS 12n Suppress messages related to \fBstate changes\fR. .RE .sp .ne 2 .na \fB\fB-t\fR\fR .ad .RS 12n Report the number of characters read and written to terminals per second. .RE .sp .ne 2 .na \fB\fB-T\fR u | d\fR .ad .RS 12n Display a time stamp. .sp Specify \fBu\fR for a printed representation of the internal representation of time. See \fBtime\fR(2). Specify \fBd\fR for standard date format. See \fBdate\fR(1). .RE .sp .ne 2 .na \fB\fB-X\fR\fR .ad .RS 12n For disks under \fBscsi_vhci\fR(7D) control, in addition to disk \fIlun\fR statistics, also report statistics for \fIlun\fR.\fIcontroller\fR. .RE .sp .ne 2 .na \fB\fB-x\fR\fR .ad .RS 12n Report extended disk statistics. By default, disks are identified by instance names such as \fBssd23\fR or \fBmd301\fR. Combining the \fBx\fR option with the \fB-n\fR option causes disk names to display in the \fBcXtYdZsN\fR format, more easily associated with physical hardware characteristics. Using the \fBcXtYdZsN\fR format is particularly helpful in the FibreChannel environments where the FC World Wide Name appears in the \fBt\fR field. .sp If no output display is requested (no \fB-x\fR, \fB-e\fR, \fB-E\fR), \fB-x\fR is implied. .RE .sp .ne 2 .na \fB\fB-Y\fR\fR .ad .RS 12n For disks under \fBscsi_vhci\fR(7D) control, in addition to disk \fIlun\fR statistics, also report statistics for \fIlun\fR.\fItargetport\fR and \fIlun\fR.\fItargetport\fR.\fIcontroller\fR. .sp In \fB-n\fR (descriptive) mode the \fItargetport\fR is shown in using the \fBtarget-port\fR property of the path. Without \fB-n\fR the \fItargetport\fR is shown using the shorter \fBport-id\fR. All target ports with the same \fBtarget-port\fR property value share the same \fBport-id\fR. The \fBtarget-port\fR-to-\fBport-id\fR association does not persist across reboot. .sp If no output display is requested (no \fB-x\fR, \fB-e\fR, \fB-E\fR), \fB-x\fR is implied. .RE .sp .ne 2 .na \fB\fB-z\fR\fR .ad .RS 12n Do not print lines whose underlying data values are all zeros. .RE .sp .LP The option set \fB-xcnCXTdz\fR \fIinterval\fR is particularly useful for determining whether disk I/O problems exist and for identifying problems. .SH OPERANDS .sp .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\fIdisk\fR\fR .ad .RS 12n Explicitly specify the disks to be reported; in addition to any explicit disks, any active disks up to the disk limit (see \fB-l\fR above) will also be reported. .RE .sp .ne 2 .na \fB\fIinterval\fR\fR .ad .RS 12n Report once each \fIinterval\fR seconds. .RE .SH EXAMPLES .LP \fBExample 1 \fRUsing \fBiostat\fR to Generate User and System Operation Statistics .sp .LP The following command displays two reports of extended device statistics, aggregated by \fIcontroller id\fR, for user (\fBus\fR) and system (\fBsy\fR) operations. Because the \fB-n\fR option is used with the \fB-x\fR option, devices are identified by controller names. .sp .in +2 .nf example% \fBiostat\fR \fB-xcnCXTdz\fR \fB5\fR Mon Nov 24 14:58:36 2003 cpu us sy dt 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 Mon Nov 24 14:58:41 2003 cpu us sy dt id 11 31 1 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 .fi .in -2 .sp .LP \fBExample 2 \fRUsing \fBiostat\fR to Generate TTY Statistics .sp .LP The following command displays two reports on the activity of five disks in different modes of operation. Because the \fB-x\fR option is used, disks are identified by instance names. .sp .in +2 .nf example% \fBiostat\fR \fB-x\fR \fBtc 5 2\fR extended device statistics tty cpu device r/s w/s kr/s kw/s wait actv svc_t %w %b tin tout us sy dt id sd0 0.4 0.3 10.4 8.0 0.0 0.0 36.9 0 1 0 10 0 0 0 99 sd1 0.0 0.0 0.3 0.4 0.0 0.0 35.0 0 0 sd6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 nfs1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 nfs2 0.0 0.0 0.0 0.1 0.0 0.0 35.6 0 0 extended device statistics tty cpu device r/s w/s kr/s kw/s wait actv svc_t %w %b tin tout us sy dt id sd0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 0 155 0 0 0 100 sd1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 sd6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 nfs1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 nfs2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 .fi .in -2 .sp .LP \fBExample 3 \fRUsing \fBiostat\fR to Generate Partition and Device Statistics .sp .LP The following command generates partition and device statistics for each disk. Because the \fB-n\fR option is used with the \fB-x\fR option, disks are identified by controller names. .sp .in +2 .nf example% \fBiostat -xnp\fR 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 .fi .in -2 .sp .LP \fBExample 4 \fRShow Translation from Instance Name to Descriptive Name .sp .LP The following example illustrates the use of \fBiostat\fR to translate a specific instance name to a descriptive name. .sp .in +2 .nf example% \fBiostat -xn sd1\fR 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 .fi .in -2 .sp .LP \fBExample 5 \fRShow Target Port and Controller Activity for a Specific Disk .sp .LP In the following example, there are four controllers, all connected to the same target port. .sp .in +2 .nf # \fBiostat -Y ssd22\fR extended device statistics device r/s w/s kr/s kw/s wait actv svc_t %w %b ssd22 0.2 0.0 1.5 0.0 0.0 0.0 0.7 0 0 ssd22.t2 0.2 0.0 1.5 0.0 0.0 0.0 0.0 0 0 ssd22.t2.fp0 0.0 0.0 0.4 0.0 0.0 0.0 0.0 0 0 ssd22.t2.fp1 0.0 0.0 0.4 0.0 0.0 0.0 0.0 0 0 ssd22.t2.fp2 0.0 0.0 0.4 0.0 0.0 0.0 0.0 0 0 ssd22.t2.fp3 0.0 0.0 0.4 0.0 0.0 0.0 0.0 0 0 .fi .in -2 .sp .SH ATTRIBUTES .sp .LP See \fBattributes\fR(5) for descriptions of the following attributes: .sp .sp .TS box; c | c l | l . ATTRIBUTE TYPE ATTRIBUTE VALUE _ Interface Stability See below. .TE .sp .LP Invocation is evolving. Human readable output is unstable. .SH SEE ALSO .sp .LP \fBdate\fR(1), \fBsar\fR(1), \fBsar\fR(1M), \fBmpstat\fR(1M), \fBvmstat\fR(1M), \fBtime\fR(2), \fBattributes\fR(5), \fBscsi_vhci\fR(7D) .SH NOTES .sp .LP The sum of \fBCPU\fR utilization might vary slightly from 100 because of rounding errors in the production of a percentage figure. .sp .LP The \fBsvc_t\fR response time is not particularly significant when the \fBI/0\fR (\fBr/s\fR+\fBw/s\fR) rates are under 0.5 per second. Harmless spikes are fairly normal in such cases. .sp .LP The \fBmpstat\fR utility reports the same \fBdt\fR, \fBusr\fR, and \fBsys\fR statistics. See \fBmpstat\fR(1M) for more information. .sp .LP When executed in a \fBzone\fR and if the pools facility is active, \fBiostat\fR(1M) will only provide information for those processors in the processor set of the pool to which the \fBzone\fR is bound.