The Ghost Town in Your Flash Array

The current state of high-performance storage is akin to a ghost town, according to an analysis by researchers at the University of California, Santa Cruz and NetApp. The study revealed that 90% of data in active, hot RAID arrays is essentially inactive, having been accessed no more than five times during its lifetime. This apparent contradiction of expensive storage housing dormant data presents a significant challenge for storage teams.

Traditional methods of archiving, such as tape offloading, have proven ineffective due to their negative impact on user workflows and increased risk exposure to ransomware attacks.

The root cause of this issue lies in the POSIX filesystem metadata system, specifically the atime (access time) timestamp. This single timestamp provides the key to identifying dormant data: if a file hasn't been accessed in some time, it is safe to relocate or purge it. However, updating atime on disk for every read operation can slow down read performance on high-throughput systems.

This dilemma is compounded by the "noatime" and "relatime" filesystem options, which either disable or limit atime updates altogether, making it difficult for engineers to identify truly inactive files.

The answer to this storage crisis is a new approach known as transparent nearline archival. This method allows data to be extracted, deduplicated, and placed in a nearline storage tier without disrupting user workflows. Unlike the traditional HSM or cold tape offloading methods, transparent nearline archival maintains fast access times for actively used data while securely storing dormant data off the primary storage path.

By implementing this solution, organizations can significantly reduce their storage costs without compromising performance or security.