This morning I received many of these on one of my DHCP-servers:

May 21 05:36:08 dns01 dhcpd: Wrote 0 deleted host decls to leases file.
May 21 05:36:08 dns01 dhcpd: Wrote 0 new dynamic host decls to leases file.
May 21 05:36:08 dns01 dhcpd: Wrote 4691 leases to leases file.
May 21 05:36:10 dns01 dhcpd: DHCPREQUEST for 10.0.117.180 (172.31.0.12) from
00:04:13:24:14:ea (73) via bond0
May 21 05:36:10 dns01 dhcpd: DHCPACK on 10.0.117.180 to 00:04:13:24:14:ea (73)
via bond0
May 21 05:36:10 dns01 dhcpd: commit_leases: unable to commit: Bad file descriptor
May 21 05:36:10 dns01 dhcpd: DHCPREQUEST for 10.0.90.202 (172.31.0.12) from
00:04:13:24:76:48 (138) via bond0: database update failed
May 21 05:36:10 dns01 dhcpd: commit_leases: unable to commit: Bad file descriptor

The server failed to hand out any leases, and its failover peer didn't
take over. After a restart, the server started working normally again.

Both failover peers run dhcp-3.0.5-4.fc6 on Fedora Core 6.

The problem may be related to this:

May 21 04:17:24 dns01 dhcpd: timeout waiting for failover peer dhcp
May 21 04:17:24 dns01 dhcpd: failover peer dhcp: I move from normal to
communications-interrupted
May 21 04:17:29 dns01 dhcpd: failover peer dhcp: peer moves from normal to
communications-interrupted
May 21 04:17:29 dns01 dhcpd: failover peer dhcp: I move from
communications-interrupted to normal
May 21 04:17:29 dns01 dhcpd: failover peer dhcp: peer moves from
communications-interrupted to normal
May 21 04:17:58 dns01 dhcpd: failover: link startup timeout
May 21 04:17:58 dns01 dhcpd: Object 802f19c0 failover-link
May 21 04:17:59 dns01 dhcpd: timeout waiting for failover peer dhcp
May 21 04:17:59 dns01 dhcpd: failover peer dhcp: I move from normal to
communications-interrupted
May 21 04:18:03 dns01 dhcpd: failover peer dhcp: peer moves from normal to
communications-interrupted
May 21 04:18:03 dns01 dhcpd: failover peer dhcp: I move from
communications-interrupted to normal
May 21 04:18:03 dns01 dhcpd: failover peer dhcp: peer moves from
communications-interrupted to normal
May 21 04:21:30 dns01 dhcpd: timeout waiting for failover peer dhcp
May 21 04:21:30 dns01 dhcpd: failover peer dhcp: I move from normal to
communications-interrupted
May 21 04:21:35 dns01 dhcpd: failover peer dhcp: peer moves from normal to
communications-interrupted
May 21 04:21:35 dns01 dhcpd: failover peer dhcp: I move from
communications-interrupted to normal
May 21 04:21:35 dns01 dhcpd: failover peer dhcp: peer moves from
communications-interrupted to normal
May 21 04:21:45 dns01 dhcpd: failover: link startup timeout
May 21 04:21:45 dns01 dhcpd: Object 80171de0 failover-link
May 21 04:21:49 dns01 dhcpd: Failover CONNECTACK from 172.31.0.13: already connected
May 21 04:21:49 dns01 dhcpd: failover peer dhcp: peer moves from normal to
communications-interrupted
May 21 04:21:54 dns01 dhcpd: Failover CONNECTACK from 172.31.0.13: already connected
May 21 04:21:59 dns01 dhcpd: Failover CONNECTACK from 172.31.0.13: already connected
May 21 04:22:04 dns01 dhcpd: Failover CONNECTACK from 172.31.0.13: already connected
May 21 04:22:09 dns01 dhcpd: Failover CONNECTACK from 172.31.0.13: already connected
May 21 04:22:11 dns01 dhcpd: timeout waiting for failover peer dhcp
May 21 04:22:11 dns01 dhcpd: failover peer dhcp: I move from normal to
communications-interrupted
May 21 04:22:14 dns01 dhcpd: failover peer dhcp: peer moves from
communications-interrupted to communications-interrupted
May 21 04:22:14 dns01 dhcpd: failover peer dhcp: I move from
communications-interrupted to normal
May 21 04:22:14 dns01 dhcpd: failover peer dhcp: peer moves from
communications-interrupted to normal