Linux bind / dhcp iowait status

[Simon Hobson]

Tom Greaser wrote:

>have a beefy box that shows 18.40 % iowait at PEAK times
>and as low as 5.50 % during work hours..
>
>have 2000 phones lease set to 1 day
>
>2000 pc lease set to 4 hours..
>
>running ddns on this host ...
>
>just wanting to see if this is "normal"
>
>will track down to see if its named or dhcpd doing the bulk of IO wait..
>
>Its an Redhat AS 4 update 3 box with mirrored scsi Ultra 320 drives
>10000 rpm
>bind-9.2.4-7
>dhcp-3.0.1
>
>from free -h
>buffer 137meg       cache 1627 meg

That sounds exceedingly high IF the box is only doing DHCP and DNS. 
In fact I'd consider 5.5% to be exceedingly high for such a box.

What else is running on the box ?

Does it make any difference if you increase lease times as Glenn suggests ?