Power management for host bus adapters
Methods and apparatus for reducing power consumption in a host bus adapter (HBA) are provided. The methods include reducing a number of active lanes in an HBA link when link traffic is low, and increasing the number of active lanes when link traffic is high.
1. A method of allocating bandwidth in a link connecting an adapter with another device in a storage area network (SAN), the method comprising:
a) evaluating an input/output (I/O) request relating to a data transfer between a host system and a storage device in the SAN;
b) determining an amount of data that will be transferred at a given time, including data associated with the I/O request; and
c) enabling or disabling lanes of the link based on the amount of data that will be transferred at the given time, including the data associated with the I/O request;
wherein when link traffic is below a first limit, a first number of lanes are enabled, and more lanes are enabled when the link traffic increases above the first limit.
2. The method of claim 1 , wherein a processor in the adapter performs steps a) through c).
3. The method of claim 1 , wherein firmware in the adapter sets limits for enabling and disabling the lanes.
4. The method of claim 1 , further comprising the step of setting a default bandwidth for the link as the first limit.
5. The method of claim 4 , wherein according to the default bandwidth one of the lanes is enabled and all other lanes are disabled.
6. The method of claim 5 , wherein according to the default bandwidth the enabled lane is enabled at generation 1 (GEN 1) speed.
7. An adapter configured to be connected via a link with another device in a storage area network (SAN), the adapter comprising:
a processor;
wherein the processor is configured to evaluate an input/output (I/O) request relating to a data transfer between a host system and a storage device in the SAN, determine an amount of data that will be transferred at a given time, including data associated with the I/O request, and enable or disable lanes of the link based on the amount of data that will be transferred at the given time, including the data associated with the I/O request.
8. The adapter of claim 7 , wherein when link traffic is low, fewer lanes are enabled and when link traffic is high, more lanes are enabled.
9. The adapter of claim 7 , further comprising firmware in the adapter configured to set limits for enabling and disabling the lanes.
10. The adapter of claim 7 , wherein according to a default bandwidth for the link one of the lanes is enabled and all other lanes are disabled.
11. The adapter of claim 10 , wherein according to the default bandwidth the enabled lane is enabled at generation 1 (GEN 1) speed.