Rory Bolt

Overview

Rory Bolt is a Senior Fellow at Kioxia who develops Flexible Data Placement (FDP) use cases and the open-source U-Frog RocksDB plugin. He identifies application classes that map well onto FDP — log-structured merge applications, circular buffers, transaction journals, and copy-on-write append-only file systems — plus any case that separates hot from cold data into different reclaim unit handles. He argues FDP succeeds where prior attempts failed because it is totally backwards compatible: users gain benefits through simple configuration changes and a phased approach without rewriting code. He notes the FDP spec lets you set a default placement ID per namespace, so multiple namespaces on a drive with different default placement IDs can map file systems or applications and separate their data automatically.

His demonstrated results are concrete. The U-Frog RocksDB plugin drove drive write amplification factor (WAF) down to essentially 1.0 (total WAF, including RocksDB compaction and file-system metadata, fell dramatically but stayed above 1.0), tested using special firmware that shrank an 8 TB drive for faster steady-state runs, and lifted RocksDB query performance from roughly 8,000 queries per second with FDP disabled to roughly 15,000 with it enabled. In a no-code CICD experiment building the Linux kernel five times in a loop with temp FS and swap space mapped to separate namespaces, WAF dropped from about 2.2 to almost exactly 1.0 with roughly 10 minutes of NVMe CLI configuration — a simple change he summarizes as over a 2x WAF decrease that effectively doubles workload service life, reduces energy consumption, and improves performance by not wasting internal device bandwidth on housekeeping.