Who should I believe - iostat or mount -v?

[Dewayne Geraghty]

While monitoring various deivces I noticed that the results from mount -v
and iostat weren't the same.  I'm "assuming" that iostat is the more
accurate due to geom tasting (on a memory disk?), or is something else at
play?

Simplest example:
mount -v -t nonullfs |grep md7; iostat -d -c 1  -tda -x -I|grep md7
/dev/md7 on /s (ufs, asynchronous, local, noatime, writes: sync 4 async
268, reads: sync 1215 async 0, fsid 8abeba5db4f71f26)
md7           1244.0       293.0          0.0          0.0    0        0.0
      0.0