Device-managed SMR (DM-SMR)
An SMR HDD that presents a conventional LBA interface while the firmware relocates writes across shingled bands.
Device-managed (drive-managed) SMR keeps shingled media behind a conventional LBA interface: firmware accepts random writes, buffers them (often using a CMR media cache), and relocates data into shingled bands during idle garbage collection. No ZAC/ZBC zone commands are exposed; Linux reports `queue/zoned` as `none`, same as CMR. There is no separate industry command-set standard for this model because it is intentionally backward-compatible. The cost is workload-dependent performance: sustained random writes without idle time can stall when the persistent cache fills and band rewrite cannot keep up. WD and others have documented DMSMR in consumer/NAS lines and advised CMR for heavy random-rewrite RAID use.
Relations
- related
- smr, hm-smr, nearline-hdd
Advantages
- Works with legacy software unaware of zoned semantics.
Limitations
- Sustained random write can trigger internal garbage collection and latency spikes.