Methods and systems for workload distribution
This invention relates to methods and systems for workload distribution, particularly in data centers, more particularly data centers which use fresh air cooling. Embodiments of the invention provide methods and systems which calculate a load value for each server which takes account of both the temperature of the server and its current job queue, and determine the server to which an incoming job should be allocated on the basis of the load values of the available servers.
1. A method for allocating jobs to a plurality of servers, wherein the jobs are tasks to be performed by the servers, the method comprising the steps of:
receiving a job to be allocated;
determining information relating to the state of each of the servers, the information comprising the temperature of each server and the amount of tasks allocated to the server and still to be performed by the server;
calculating a thermal load of each server using both the temperature of the server and the amount of tasks allocated to the server and still to be performed by the server;
choosing the server to allocate the job to according to the calculated thermal loads of the servers, wherein the step of choosing chooses the server with the lowest calculated thermal load; and
allocating the job to the chosen server; and
where the thermal load of each server is calculated as:
ThermalLoad=Temperature× e queueLength
wherein queueLength is a representation of the amount of tasks allocated to the server and still to be performed by the server.
2. A method according to claim 1 where the temperature of the server which is determined is the temperature of a CPU in the server.
3. A method according to claim 1 including the further steps of:
switching a server to an idle state if the temperature of that server exceeds an upper temperature threshold; and
switching a server in an idle state to an active state when the server temperature reaches a lower temperature threshold.
4. A system for allocating jobs to a plurality of servers, wherein the jobs are tasks to be performed by the servers, the system including:
a load balancer;
a plurality of servers, each having a temperature sensor arranged to measure the temperature of the server; and
a network connecting said servers and said load balancer,
wherein the system is arranged to:
determine information relating to the state of each of the servers, the information comprising the temperature of each server and the amount of tasks allocated to the server and still to be completed by the server; and
calculate a thermal load of each server using both the temperature of the server and the amount of tasks allocated to the server and still to be performed by the server,
and the load balancer is arranged to:
receive a job to be allocated;
choose a server to allocate the job to according to the calculated thermal loads of the servers, wherein the load balancer chooses the server with the lowest calculated thermal load to allocate the job to; and
allocate the job to the chosen server; and
where the thermal load of each server is calculated as:
ThermalLoad=Temperature× e queueLength
wherein queueLength is a representation of the amount of tasks allocated to the server and still to be performed by the server.
5. A system according to either claim 4 where the temperature sensors measure the temperature of a CPU in each server.
6. A system according to claim 4 , wherein if the temperature of a server exceeds an upper temperature threshold, the server switches to an idle state until the server temperature reaches a lower temperature threshold when it switches to an active state.
7. A system according to claim 6 further including active cooling apparatus, wherein the active cooling apparatus actively cools a server which is running idle.
8. A system according to claim 4 wherein the load balancer is also a server.
9. A load balancing device for allocating jobs to a plurality of servers, wherein the jobs are tasks to be performed by the servers, the load balancing device having a processor and being arranged to:
receive a job to be allocated to a server, and
receive information from each of the servers, the information comprising the temperature of the server, and the amount of tasks allocated to the server and still to be completed by the server,
and wherein the processor:
calculates a thermal load of each server using both the temperature of the server and the amount of tasks allocated to the server and still to be performed by the server;
chooses a server to allocate the job to according to the calculated thermal loads of the servers, wherein the processor chooses the server with the lowest thermal load to allocate the job to; and
allocates the job to said chosen server; and
wherein the processor calculates the thermal load of each server as:
ThermalLoad=Temperature× e queueLength
wherein queueLength is a representation of the amount of tasks allocated to the server and still to be performed by the server.
10. A load balancing device according to claim 9 wherein the temperature of each server is the temperature of a CPU in the server.