failover timeout

Glenn Satchell glenn.satchell at
Thu Apr 8 14:39:24 UTC 2010

4,2.0 (currently alpha) has a configurable auto-partner-down feature. 
For all earlier releases the server stays in communications-interrupted 
and *never* goes to partner down mode without manual action. 
Partner-down is the mode where the surviving server can allocate 
addresses previously given out by the failed server.

Having said that it is pretty easy to write a script that monitors the 
other dhcp server, and uses omshell to switch to partner down when it 
detects that the other server has gone away. When the failed server 
comes back it will come out of partner-down mode and return to normal as 
part of the startup negotiations.

There was a post to the list by David Hankins on 25 Feb this year 
mentioning this which gives a lot more detail.


On 04/08/10 13:48, Abu Abdulla alhanbali wrote:
> this is not what i mean. if the primary servers is down, how long will
> it take the secondary server to start assigning the IPs that are
> reserved for the primary server. you can do this manually using the
> omshell but i don't know if this will be done automatically or not.
> On Wed, Apr 7, 2010 at 7:55 PM, Banana Flex<flex.banana at>  wrote:
>> hi
>> you can do a collaboration betwen two servers that send the same subnet, see the man page of dhcpd.conf for many information. you can also configure the timeout. 3 seconds is a good choice
>> have fun
>> Banana
>> On Apr 7, 2010, at 5:41 AM, Abu Abdulla alhanbali wrote:
>>> Hi,
>>> i would like to know how long it will take the secondary DHCP server
>>> to start assigning IPs for all users (including the ranges dedicated
>>> to the primary) in case the primary DHCP is down? is it a
>>> configurable?
>>> i would like also to ask if the DHCP can handle 200K users or above
>>> assuming the H/W is capable and the lease time is big enough (more
>>> than one week). is it recommended to run multiple instances or let one
>>> instance handle this number.
>>> thanks

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