[SunHELP] How to determine what causes a disk is busy

[sunhelp at sunhelp.org]

I run iostat to check disk activity and suspect the disk is so busy by
looking at column %b.  How do I find out what causes the disk busy?  I
run Solaris8.  Thanks.

#iostat -x 1 10
                  extended device statistics
device       r/s    w/s   kr/s   kw/s wait actv  svc_t  %w  %b
sd0         75.0   66.3 1731.2  520.4  0.1  4.1   29.6   0  92
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
                  extended device statistics
device       r/s    w/s   kr/s   kw/s wait actv  svc_t  %w  %b
sd0         50.6   67.4 4782.5  539.3  0.0  3.1   26.4   0 100
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
                  extended device statistics
device       r/s    w/s   kr/s   kw/s wait actv  svc_t  %w  %b
sd0         42.0   74.0 4064.1  592.0  0.0  3.6   31.2   0 100
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