Why the usage of disks exceed %100 in systat command ?

[Halid Faith]

Hello
I have a machine which have Raid5 and Freebsd6.0 runs on it.

When I type in command line as below I sometimes see a thing.
systat 1 -vmstat

    3 users    Load  0.00  0.00  0.00                  Mar 21 21:03
Mem:KB    REAL            VIRTUAL                     VN PAGER  SWAP PAGER
        Tot   Share      Tot    Share    Free         in  out     in  out
Act   35552    3144   110592     6776  112592 count
All 2028148    6116  8433668    16144         pages
                                                                 Interrupts
Proc:r  p  d  s  w    Csw  Trp  Sys  Int  Sof  Flt     15 cow    8216 total
     2     8 45      3039   86 2001 1385    5   84 187364 wire        1:
atkb
                                                    39176 act         6:
fdc0
 1.8%Sys   0.4%Intr  0.7%User  0.0%Nice 97.1%Idl  1711860 inact       13:
npx
|    |    |    |    |    |    |    |    |    |      93272 cache       15:
ata
=                                                   19320 free     83 21:
amr
                                                          daefr   149 28:
fxp
Namei         Name-cache    Dir-cache                  24 prcfr       29:
mpt
    Calls     hits    %     hits    %                     react  1996 cpu0:
time
      394      301   76       14    4                     pdwak  1996 cpu3:
time
                                       52 zfod            pdpgs  1996 cpu1:
time
Disks amrd0 pass0                      52 ofod            intrn  1996 cpu2:
time
KB/t   6.04  0.00                         %slo-z   114464 buf
tps      86     0                      64 tfree        58 dirtybuf
MB/s   0.50  0.00                                  100000 desiredvnodes
% busy  119     0                                   85778 numvnodes
                                                    24996 freevnodes

I see that usage of the disk % more than 100.
does this condition become any problem?
Might  this condition which raid card does not work properly be ?