Abstract
NetApp®WAFL®is a transactional file system that uses the copy-on-write mechanism to support fast write performance and efficient snapshot creation. However, copy-on-write increases the demand on the file system to find free blocks quickly; failure to do so may impede allocations for incoming writes. Efficiency is also important, because the task may consume CPU and other resources. This talk describes the evolution (over more than a decade) of WAFL’s algorithms and data structures for reclaiming space with minimal impact on the overall storage appliance performance. The talk also presents a quick summary of WAFL topics that have been recently published in ICPP 2016, OSDI 2016, FAST 2017, and ICPP 2017.