DHCP failover - disk full, can not commit to lease file

[Louis Lau]

Dear all,

I have two DHCP servers configured as failover peer and the router relay the DHCP/Bootp request to both server. When the system works normaly, a DHCP discover from client will be broadcast to both server and the observed behavour is that both server will offer an DHCP OFFER to the same client, The primary DHCP server shall reply an IP-A managed by the Primary, and the Secondary shall reply an IP-B that is managed by the secondary. Assume the client select IP-A and send an DHCP Request for IP-A to both server.

However recently, primary server disk is full, and in the log there are a lot of

ommit_leases: unable to commit: No space left on device

We observed that the DHCP does not failover to the secondary in this case, and the primary will still response to DHCPDISCOVER and provide a DHCP Offer.  And in this case, we observed that most client does not try the DHCP offer from secondary but most of them choose the IP assigned from the Primary DHCP server.

Is this behaviour normal?

Are there any configuration that can make the server fail to secondary DHCP server for similar case or let the client try the other DHCP OFFER when the first DHCP IP does not have a ACK?

Thanks for your help on this matter.

Louis Lau

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