Sudden Slow Performance

Mon Dec 15 15:53:40 UTC 2008

Try running strace against the DHCP pid and see if it is trying to access a resource that is not available or is running slow, like DNS.

>>> "Kelvin Williams" <kelvin-lists at williamschadwell.com> 12/15/2008 8:47 AM >>>
I just executed a sniff on the DHCP Server.  This is for ONE client.  

TimeMessageTransaction ID
21sDISCOVER0x1179
25sOFFER0x1179
26sDISCOVER0x117a
34sOFFER0x117a
35sDISCOVER0x117b
44sOFFER0x117b
46sREQUEST0x117b
50sREQUEST0x117b
54sACK0x117b
58sACK0x117b

The client is getting all messages; but appears to be giving up and starting
again after the wait.

kw

-----Original Message-----
From: dhcp-users-bounces at lists.isc.org 
[mailto:dhcp-users-bounces at lists.isc.org] On Behalf Of Tom Greaser
Sent: Monday, December 15, 2008 10:10 AM
To: 'Users of ISC DHCP'
Subject: RE: Sudden Slow Performance

Have you sniffed / snooped a station to see if its getting this Offer / ACK
?

>>> "Kelvin Williams" <kelvin-lists at williamschadwell.com> 12/15/08 9:52 AM
>>> 
The entire network. 

-----Original Message-----
From: dhcp-users-bounces at lists.isc.org 
[mailto:dhcp-users-bounces at lists.isc.org] On Behalf Of Tom Greaser
Sent: Monday, December 15, 2008 9:47 AM
To: 'Users of ISC DHCP'
Subject: RE: Sudden Slow Performance

Is this effecting All of your network or just a few subnets ?

Ive had issues like this.. but only for specific networks.. I had a switch
that
would auto prune spanning tree .. Thus i would get the  DHCPDISCOVER  but
never the clients would never see the 
DHCPOFFER.  

I manually made sure that network was never pruned..  

>>> "Kelvin Williams" <kelvin-lists at williamschadwell.com> 12/15/08 9:38 AM
>>> 
Network good.  No errors on the interfaces.

No disk errors reported.

No patches applied.

CPU and Memory levels are good.

Number of clients always increases--but not a drastic amount.  Maybe 50 new
clients.

-----Original Message-----
From: dhcp-users-bounces at lists.isc.org 
[mailto:dhcp-users-bounces at lists.isc.org] On Behalf Of Glenn Satchell
Sent: Monday, December 15, 2008 9:25 AM
To: dhcp-users at lists.isc.org 
Subject: Re: Sudden Slow Performance

>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

_______________________________________________
dhcp-users mailing list
dhcp-users at lists.isc.org 
https://lists.isc.org/mailman/listinfo/dhcp-users 

_______________________________________________
dhcp-users mailing list
dhcp-users at lists.isc.org 
https://lists.isc.org/mailman/listinfo/dhcp-users 

_______________________________________________
dhcp-users mailing list
dhcp-users at lists.isc.org 
https://lists.isc.org/mailman/listinfo/dhcp-users 

_______________________________________________
dhcp-users mailing list
dhcp-users at lists.isc.org 
https://lists.isc.org/mailman/listinfo/dhcp-users 

_______________________________________________
dhcp-users mailing list
dhcp-users at lists.isc.org 
https://lists.isc.org/mailman/listinfo/dhcp-users 

_______________________________________________
dhcp-users mailing list
dhcp-users at lists.isc.org 
https://lists.isc.org/mailman/listinfo/dhcp-users

CONFIDENTIALITY NOTICE:  The information contained in this e-mail is privileged and confidential, and is intended only for the use of the individual or entity named above.  If you are not the intended recipient, you are notified that any disclosure, copying, distribution, electronic storage or use of this communication is prohibited.  If you received this communication in error, please notify us immediately by e-mail, attaching the original message, and delete the original message from your computer and any network to which your computer is connected.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20081215/3ae3b50e/attachment-0001.html>