A fast SSD is only as fast as the software telling it what to do. Researchers at KAIST found that the operating system has been holding back a newer type of flash storage, and they built a filesystem technology called GAZE to fix it.
EurekAlert reports that the team, led by Professor Youjip Won, presented its work at ACM SOSP 2026 in Prague.
What is slowing down ZNS flash storage?
Flash drives cannot write new data over old data. To reuse space, the drive has to copy the data worth keeping to a new spot and wipe the rest. This housekeeping job is called garbage collection.
The KAIST team focused on ZNS storage, which splits a drive into large zones that can hold gigabytes of data each. That keeps the drive simple but hands cleanup to the filesystem, which was built to clean much smaller areas.
In the team’s tests, cleaning a single 1 GB zone took about 1.7 seconds, or 283 times longer than cleaning a 2 MB section. New writes were stuck waiting the entire time. Oddly enough, more than 70% of the delay came from CPU work, like checking which data was still valid and handling memory, rather than from the drive.
How does GAZE fix the cleanup problem?
GAZE splits cleanup into four overlapping steps, so it reads the next batch of data while still writing the last one. It also reserves memory for cleanup ahead of time instead of requesting it piece by piece. Meanwhile, writes that can sit in memory briefly no longer wait for cleanup to finish.
GAZE delivered up to 3x the performance of the standard setup and earlier fixes like ZNS+ and P-GC, and it cut cleanup time to about one-third. It does not need special hardware or changes to how data is stored on the drive.
Professor Won said, “This study is significant because we completely removed the operating-system bottleneck that prevented fast flash storage devices from being fully utilized.”
This matters most for AI inference, where processors need data on time and lose efficiency while they sit idle. If GAZE reaches data centers, the fast storage they already pay for could finally deliver its full speed.
