Host-managed SMR (HM-SMR)
An SMR HDD whose shingled bands are exposed to the host, which must write sequentially within zones.
Host-managed SMR exposes sequential-write-required zones: the host (or zoned filesystem) must write at the zone write pointer; out-of-order writes are rejected. Zone report/reset/finish commands come from SCSI ZBC or ATA ZAC with aligned semantics. Linux identifies host-managed disks as zoned block devices (`queue/zoned` = host-managed); SCSI type 0x14 or SATA signature 0xabcd distinguish them from ordinary disks. Unlike drive-managed SMR, there is no firmware mask for random block I/O—integration needs zone-aware software (e.g., zonefs, SMR-aware object layers). Vendors place top nearline capacities on HM-SMR because the host can keep writes sequential and performance predictable.
Relations
- related
- smr, device-managed-smr, zns
Advantages
- Host software can optimize placement for append-heavy workloads.
Limitations
- Requires OS or application support for zoned block or zoned ATA commands.