If compaction (= defragmentation) runs continuously or near-continuously, it results in write amplification of 2x or more. For a home/small-office NAS (the topi

If compaction (= defragmentation) runs continuously or near-continuously, it results in write amplification of 2x or more. For a home/small-office NAS (the topic at hand) that's also lightly used with a read-heavy workload, it should be fine to rely on compaction to keep things running smoothly, since you won't need it to run that often and you have cycles and IOPS to spare. If, under those conditions, 100 GB has proven to be enough for a lot of users, then it might make sense to add more flexible alarms. However, this workload is not universal, and setting such a low limit (0.5% of 20 TB) in general will not reflect the diverse demands that different people put on their storage.