Application Scenarios

Ucache is suitable for hybrid-flash storage (HDD backend storage + NVMe cache) where the read performance needs to be improved.

Ucache is developed based on the open source ocf project. ocf is a cache engine that uses high-performance storage devices to accelerate backend block storage I/O access. It requires configuring the adaptation layer (external APIs).

In the Lava scenario, to integrate a read cache on the server side, refer to the following solution of implementing the read cache module based on ocf:

• Lava is a complete storage solution. Read cache integration on the server side does not require the integration of the entire ocf framework. Only some algorithm logic such as the mapping between cached data and data in main storage as well as data eviction needs to be reused. Other functions can be cropped as required.
• An adaptation layer needs to be added for the Lava system. Reserve information such as slots and regions of input I/Os. The adaptation layer automatically converts lava_io to ocf_io, facilitating quick integration with the Lava system.
• To read and write data in the read cache, the Lava system needs to provide block read and write interfaces. The chunk layer of Lava provides NVMe chunk pools and asynchronous chunk read/write interfaces.