Sudden Slow Performance

[Glenn Satchell]

>From: "Kelvin Williams" <kelvin-lists at williamschadwell.com>
>To: <dhcp-users at lists.isc.org>
>Subject: Sudden Slow Performance
>Date: Mon, 15 Dec 2008 08:57:08 -0500
>X-Spam-Level: ***
>X-BeenThere: dhcp-users at lists.isc.org
>
> We've been operating one of our DHCP Servers for approximately 6 months
> without any issues.  This server is on a network with about 2,500 hosts.
> The server has worked flawlessly until last week when it became extremely
> slow. 
> 
> Clients are having to send multiple DISCOVERs before the server will
> respond, and sometimes the server does not respond timely to a REQUEST.
> Causing the clients to timeout and stop attempting.
> 
> We've reviewed the server's load, and its very, very light.  vmstat doesn't
> show any bottlenecks in the processor or disk.  The current version we are
> running is 3.1.1; 
> 
> As I stated, this all occurred within the last week.  Can anyone recommend
> something to check?  Or is there a way to get greater verbosity from the
> debug mode?
> 
> Many thanks in advance.
> 
> Kw

Have you checked out the hardware, network, etc? Maybe there is a hardware 
fault. Consider the slow dhcp response to be a symtim rather than the fault?

Could be a number of things:

- faulty network. try a different cable and/or switch port and/or nic

- disk errors. check logs for warnings or errors

- operating system patches. done any os patches around the time it went bad?

- any other system changes at that time?

- rogue process using all available cpu or memory?

- did the number of clients increase that week?

regards,
-glenn