yhpcd will not start.
It is probably already running. Therefore, you just kill it (as root):

killall -9 yhpcd

... try starting it again.


yhpcgui won't start.
Make sure the yhpcd daemon is running (as root):

service yhpcd restart

DHCP is not handing over to netboot (Apple).
The latest version of the DHCP Daemon does not work correctly with Apple, you must install dhcp v3.0pl1 which is included with the Y-HPC ISO.


Why are there 2 IP ranges in the dhcp configuration?
There are now two IP ranges (the static range we had before), and another temporary range, both user definable...  Now, when a node first boots and is not in the system yet, DHCP hands out only one of the short lease temporary IP address.  This address is only used for the first connection to the system.  When the node is added by Y-HPC, Y-HPC performs a search (hashing and linear scan, so it's effectively a O(n) scan + hashing overhead) for a free static address and adds the node to the system with this assigned IP address.


DHCP has no address available.
The temporary range of IP addresses is for imaging only, then a node is assigned a static IP. When imaging lots of nodes the temporary range can be completely used. In this case removing the /var/lib/dhcp/dhcp.leases file and restarting dhcpd should fix the issue.


What to do if a compute node dies?
You need edit only one file to edit:

1. Kill off yhpcd and yhpc-gui via:

   service yhpcd stop [ENTER]

2. Edit /var/lib/yhpc/yhpc.xml and delete the .... entry for the dead node and then change the ID for the last node to the dead node.
   
   
3. Restart yhpcd/yhpc-gui