Question on shredding a terebyte drive

[Dean S. Messing]

Rick Stevens wrote:
> >  4) I don't know if the fact that the process runing at 100% of one CPU
> >     means it is compute bound.  Looking at the disk I/O meter in
> >     gkrellm I see bursts of writes followed by intervals of no
> >     transfer.  I know that magnetic reorientation requires some time
> >     to "set" and that may be why the delays are there.  Or it may be
> >     compute bound.
> 
> Run "top" and you may find that the shred process is in a "D" state a
> lot of the time.  That means it's in an I/O wait state, waiting on the
> drive to complete some operation.  A "D" state can suck up a lot of CPU.

Thanks Rick.  It's in "D" state only about 5-10% of the time.  Yet
disk writes are occuring (according to the spikes and numbers in
gkrellm) for 1 second or so, every 2 seconds.  So that either points
to random number computation or the wait needed to let the new
magnetic orientation 'set'. Not sure.

Dean