NAME

iost+ - Extended version of iostat

SYNOPSIS

iost+ [ interval [ count ] ]

DESCRIPTION

iost+ is an extended version of iostat, written in perl using the Solaris::MapDev and Solaris::Kstat modules. By default the kernel statistics are sampled every 5 seconds. If a single parameter is given it is used as the sample interval. If a second parameter is given it is used as the number of samples to display.

OPERANDS

The following operands are supported:

interval

The time between each sucessive sample, in seconds

count

The number of samples to display

EXAMPLES

$ iost+ 5 3
iost+ started on 19/11/1998 15:51:30 1998 on fubar

15:51:35 --throughput-- -----wait queue----- ----active queue----
 r/s  w/s   Kr/s   Kw/s qlen res_t svc_t %ut qlen res_t svc_t %ut device
  49    0     38      0  0.0   0.0   0.0   0  0.9  18.6  18.5  90 nfssvr:/fs1
   0    4      0     25  0.0   0.0   0.0   0  0.5 128.5   9.7   4 c0t0d0
   0   75      0    571  0.0   0.0   0.0   0  8.5 112.6  11.8  89 c0t10d0
   0   75      0    568  0.0   0.0   0.0   0  9.3 125.0  13.1  98 c0t9d0
  11    0    112      0  0.0   0.0   0.0   0  1.0  88.7  88.7  99 mt1
   0  154      0   1164                                           TOTAL DISK
  49    0     38      0                                           TOTAL NFS
  11    0    112      0                                           TOTAL TAPE

15:51:40 --throughput-- -----wait queue----- ----active queue----
 r/s  w/s   Kr/s   Kw/s qlen res_t svc_t %ut qlen res_t svc_t %ut device
  51    0     39      0  0.0   0.0   0.0   0  0.9  17.5  17.4  89 nfssvr:/fs1
   0    1      0      8  0.0   0.0   0.0   0  0.0  28.2   9.1   1 c0t0d0
   0   70      0    525  0.0   0.0   0.0   0 10.7 152.8  13.4  94 c0t10d0
   0   71      0    528  0.0   0.0   0.0   0 11.4 160.6  13.4  95 c0t9d0
  11    0    113      0  0.0   0.0   0.0   0  1.0  87.9  87.9  99 mt1
   0  142      0   1061                                           TOTAL DISK
  51    0     39      0                                           TOTAL NFS
  11    0    113      0                                           TOTAL TAPE

15:51:45 --throughput-- -----wait queue----- ----active queue----
 r/s  w/s   Kr/s   Kw/s qlen res_t svc_t %ut qlen res_t svc_t %ut device
  53    0     51      0  0.0   0.0   0.0   0  0.9  17.0  17.0  89 nfssvr:/fs1
   0   75      0    563  0.0   0.0   0.0   0 13.7 183.6  12.4  92 c0t10d0
   0   75      0    564  0.0   0.0   0.0   0 13.9 186.2  12.8  96 c0t9d0
  11    0    111      0  0.0   0.0   0.0   0  1.0  89.4  89.4  99 mt1
   0  149      0   1127                                           TOTAL DISK
  53    0     51      0                                           TOTAL NFS
  11    0    111      0                                           TOTAL TAPE

iost+ finished at 19/11/1998 15:51:45 1998 on fubar
$ 

Note that statistics for devices are only displayed when there is some activity on the device, and that disk, nfs and tape statistics are shown. The total throughput for each class of device is shown at the bottom of each set of statistics.

The statistics for each device are split into three logical groupings:

Throughput

This is the basic I/O performance of the device, expressed in physical reads and writes per second as well as kilobytes read and written per second.

Wait Queue

Solaris measures two sets of I/O statistics. The wait queue values are the performance statistics for the device driver.

Active Queue

The active queue values are the performance statistics of the physical device.

The meaning of the individual columns is as follows:

r/s     reads per second
w/s     writes per second
Kr/s    kilobytes read per second
Kw/s    kilobytes written per second
qlen    average queue length
res_t   average response time per request
svc_t   average service time per request
%ut     percent utilisation

AUTHOR

Alan Burlison, <Alan.Burlison@uk.sun.com>

SEE ALSO

iostat(1M)

"Sun Performance And Tuning - Java And The Internet" 2nd ed. by Adrian Cockroft and Richard Pettit - ISBN 0-13-095249-4.

iost+ is a reimplementation of the siostat.se script in perl, with a few cosmetic differences. Refer to pages 194-198 of the book for a full explanation of the statistics and how they are calculated.