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The Drive That Doubles Areal Density with Lasers — And Proves the Physics Works at Scale

Every hard drive in production today uses PMR (Perpendicular Magnetic Recording) or its derivatives. Seagate’s Exos 2X18 uses something fundamentally different: HAMR (Heat-Assisted Magnetic Recording), where a tiny laser heats each magnetic bit to the Curie point before writing, enabling denser bit packing on the platter. HAMR is not a marketing name — it is a physics breakthrough that Seagate has shipped in volume since 2023. The Exos 2X18 is the 18TB production drive that proves the technology works in enterprise environments: 2.5 million hours MTBF, 550 TB/year workload, CMR recording, and a 5-year warranty.

Технические характеристики

Параметр	Спецификация
Емкость	18ТБ (dual actuator: 2x 9TB logical volumes)
Фактор формы	3.5-дюйм LFF
Интерфейс	SAS 12 Гбит/с (dual-port) or SATA 6Gb/s (single-port)
Скорость вращения	7,200 Rpm
Recording Technology	HAMR (Heat-Assisted Magnetic Recording), CMR organization
Actuators	2x independent actuators (MACH.2 dual-actuator technology) — each actuator services half the drive (9TB per actuator)
Cache Buffer	512 МБ
Sustained Transfer Rate	Вплоть до 288 МБ/с (combined dual-actuator throughput up to ~570 MB/s)
Average Latency	4.16 ms
Среднее время безотказной работы	2,500,000 часы
Workload Rate Limit	550 TB/year
URE Rate	1 sector per 10^15 bits
Власть (Праздный / Операционная)	4.5Вт / 7.5Вт
Sealing	Helium-sealed (HelioSeal)
Размер сектора	512e or 4Kn
Физический	147.0 Икс 101.85 Икс 26.1 мм, 690г
Температура	5C to 60C
Гарантия	5-ограничено годом (производитель)

MACH.2 Dual-Actuator — Two Drives in One Enclosure

The Exos 2X18’s defining feature is not the laser — it is the dual-actuator design. Two independent actuator arms, each with its own head stack, service two separate 9TB logical volumes on the same platters. The operating system sees two separate drives (da and db), each with 9TB, each capable of ~144 MB/s sustained throughput. Combined, the drive delivers ~288 MB/s — effectively two drives in one enclosure. This doubles sequential throughput per drive bay, which is why the 2X18 is deployed in object storage (MinIO), backup repositories, and media archives where sequential throughput per bay is the scaling metric.

HAMR vs PMR vs MAMR — The Recording Technology Comparison

Особенность	PMR (current standard)	HAMR (Seagate Exos 2X18)	MAMR (Toshiba MG10)
Recording Mechanism	Perpendicular magnetic recording, no laser	Laser heats bits to Curie point before writing	Microwave-assisted, no laser
Areal Density Potential	~2.5 Tb/in2 (practical ceiling)	Вплоть до 10 Tb/in2 (theoretical), 2.4 Tb/in2 today	~3.5 Tb/in2 (theoretical)
Production Status	Mature, all vendors	In volume production (Seagate)	In volume production (Toshiba)
Capacity Ceiling (2026)	~24TB (PMR-derived ePMR/FC-MAMR)	~30TB+ (HAMR path continues past PMR limits)	~24TB
Risk Profile	Zero (proven)	Low (3+ years of production data)	Low
Лучшее для	All workloads, conservative buyers	Capacity-dense deployments, object storage, резервная копия	Mixed workloads, capacity tiers

Совместимые платформы

SAS 12Gb/s dual-port variant compatible with all servers with SAS backplanes. SATA variant compatible with SATA backplanes. Dell PowerEdge R660/R760/R770, xFusion V7, Lenovo ThinkSystem, MinIO nodes, TrueNAS. MACH.2 dual-actuator support requires OS support: Linux kernel 5.10+ (dm/multipath or two-disk mode), Windows Server 2019+ (two-disk mode), VMware ESXi 7.0+ (two-disk mode).