Join us at the CRSS Seminar, where Sara McAllister will present a talk on Overcoming Write Limitations to Achieve Sustainable Flash Caching.

Abstract:

By 2050, data centers are projected to account for 33% of the global carbon emissions. Unfortunately, data centers cannot just switch to renewable energy to solve this problem since the majority of their carbon emissions are embodied, generated from lifecycle events like manufacturing. However, reducing embodied emissions for storage (40% of server emissions) has been previously overlooked. One key way to reduce embodied emissions is to increase device lifetime, but this is challenging for flash SSDs where longer lifetimes decrease their yearly write budget. For flash caches in particular, these write limits prohibit extended lifetimes that would enable sustainable caches.

In this talk, I will present two flash cache designs I have created to minimize writes and achieve sustainable flash caches. To tackle application writes and reduce misses, I will first introduce Kangaroo, a flash cache for tiny objects. Unfortunately, I will show that Kangaroo cannot remove all device-level writes and thus cannot handle future, more write-limited but also more sustainable flash caching. Thus, I will then present FairyWREN, a flash cache co-designed with a new class of flash interfaces that eliminates these extra writes, reducing writes by 12.5x over Kangaroo. Without these writes, FairyWREN reduces the flash carbon emissions by 33% over Kangaroo.

Bio:

Sara McAllister is a 5th-year PhD student at Carnegie Mellon University, advised by Nathan Beckmann and Greg Ganger. She is interested in computer systems, particularly caching and storage systems. Her work includes a focus on improving efficiency and sustainability through hardware-software co-design and grounding design choices in mathematical modeling. Her work has appeared at OSDI and SOSP, including receiving a Best Paper Award at SOSP 2021. Sara also has been awarded a NDSEG fellowship and is an EECS Rising Star 2023.