Add the relevant networks into the DHCP configuration, refer to: Setup-dhcp
Add the defined nodes into the DHCP configuration, refer to: XCAT_pLinux_Clusters/#configure-dhcp
In the large cluster, the size of dhcp lease file "/var/lib/dhcpd/dhcpd.leases" on the DHCP server will grow over time. At around 100MB in size, the DHCP server will take a long time to respond to DHCP requests from clients and cause DHCP timeouts: :
...
Mar 2 01:59:10 c656ems2 dhcpd: DHCPDISCOVER from 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPOFFER on 9.114.39.101 to 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPREQUEST for 9.114.39.101 (9.114.39.157) from 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPACK on 9.114.39.101 to 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPDECLINE of 9.114.39.101 from 00:0a:f7:73:7d:d0 via eth0: not found
Mar 2 01:59:10 c656ems2 dhcpd: DHCPDISCOVER from 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPOFFER on 9.114.39.101 to 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPREQUEST for 9.114.39.101 (9.114.39.157) from 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPACK on 9.114.39.101 to 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPDECLINE of 9.114.39.101 from 00:0a:f7:73:7d:d0 via eth0: not found
Mar 2 01:59:10 c656ems2 dhcpd: DHCPDISCOVER from 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPOFFER on 9.114.39.101 to 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPREQUEST for 9.114.39.101 (9.114.39.157) from 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPACK on 9.114.39.101 to 00:0a:f7:73:7d:d0 via eth0
Mar 2 01:59:10 c656ems2 dhcpd: DHCPDECLINE of 9.114.39.101 from 00:0a:f7:73:7d:d0 via eth0: not found
...The solution is simply to restart the dhcpd service or run makedhcp -n.