iostat command shows incorrect values

Issue

• When we execute command iostat 3 2 on our production server at first time it shows very high value and thereafter it shows proper values.

Sample output is as follows :-

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          12.41    0.00    1.81    1.55    0.00   84.23

Device:   tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda                    215.82             16049.26      5674.14 115871138897 40965666846
sdb               0.00         0.00         0.00       3560          0

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           1.47    0.00    0.13    0.08    0.00   98.32

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda              20.67         5.33       386.67         16       1160
sdb               0.00         0.00         0.00          0          0