You use the Hosts page both as a means of checking on how efficiently the hosts's resources are being used and as a way to access more details about the host itself.
The fields in the Host table have the following meaning:
Hostname – The name you assign to this host. Clicking the Hostname displays the very detailed Host Details page.
Arch – The host's processor architecture like win32-x86 or sol-sparc64. For a complete list of supported architectures, see the Host Details page.
Average Load/CPU – Shows how efficiently the Host's CPU is being used. This parameter can be any positive decimal number but is usually between zero and 2 or 3. Ideally, this number should be close to 1. A smaller number could mean the host is under-utilized, and a larger number could mean that the host is overutilized. The ideal value depends on the workload that is being run. Only the local administrator can really know the implications of the workload.
Used Mem – The percentage of total memory currently being used to execute jobs. If this value is too close to the total memory, then the host is possibly in trouble. However, if the workloads are tuned to fit in the server, then it could be perfectly fine that the used memory is just under the total memory. In fact, this is tunable: you can set the value at which the difference between these two parameters triggers an alarm. So, in one case, a difference of less than 100 MB triggers a warning, while in another case the value could be set at 25 MB.
Total Mem – The total amount of memory on this host.
Free Swap – The amount of free swap space left on this host measured in MBs. In a well-architected grid, the free swap space should never drop very far below its initial value. It is possible that temporary drops in this value can be tolerated, again, depending on how the grid is architected. If this value goes close to zero, the host is in danger of failing completely.