iostat usage and output

Question

When I run the iostat command like this:

iostat -d

I get a result something like this:

Linux 2.6.18-238.el5 (mon01)       09/03/2011

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda               9.83        11.88       264.67   38378414  854835288
sda1              9.83        11.88       264.67   38375658  854834320
sda2              0.00         0.00         0.00       2346        968
sdb              58.40         7.96      1552.02   25716671 5012803778
sdb1             58.40         7.96      1552.02   25715861 5012803778

If I run it again several times waiting two to three few minutes between execution I get exactly the same set of values for tps, Blk_read/s and Blk_wrtn/s. The man page for iostat says:

The first report generated by the iostat command provides statistics concerning the time since the system was booted. Each subsequent report covers the time since the previous report.

If this is the case why are my tps, Blk_read/s and Blk_wrtn/s values not varying in the slightest?

Does "Each subsequent report" mean between the individual reports if running:

iostat -d 1 5

...rather than the last time I ran iostat -d?

I am slightly confused here.

Answer 1

Yeah you already answered it. The subsequent is for subsequent repeats of the report by the same iostat command, not between executions of the command(those are always since boot).