Samsung MZILS400HEGR0D3 400GB PM1635a SAS 12Gb/s 2.5 inch Enterprise Solid State Drive

General

Brand	Samsung
Model	PM1635a
Capacity	400GB
Usage Class	Enterprise

Interface

Host Interface	SAS 12Gb/s
Total Interface Bandwidth	12 Gb/s

Physical Dimension

Form Factor	2.5

Flash & Endurance

NAND Flash	Samsung V-NAND 3bit MLC (TLC)
Drive Writes Per Day	3
Total Bytes Written	2190 TBW

Performance

Sequential Read	1200 MB/s
Sequential Write	900 MB/s
Random Read IOPS	190000
Random Write IOPS	35000
Average Latency	110 μs

Reliability

Mean Time Between Failures	2 Million Hours
Uncorrectable Bit Error Rate	1.0×10⁻¹⁷
Power Loss Protection	Yes

Part Number

MPN	MZILS400HCGR

Engineer's Note

Compared with the earlier MZILS400HCGR, the Samsung PM1635a (MZILS400HEGR0D3) moves to a newer V-NAND TLC platform and fully leverages the 12Gb/s SAS interface to deliver up to 1200/900 MB/s and 190K/35K IOPS, giving this 400GB tier stronger throughput and random-read density for enterprise arrays. With 3 DWPD and 2190 TBW, it is a solid fit for mixed-read virtualization, database logging, and boot-optimized server storage where you need SAS reliability with better endurance-per-drive than typical read-centric SSDs.

Endurance & Reliability

With an endurance rating of 2,190 TBW and 3 DWPD, the MZILS400HEGR0D3 is designed for sustained enterprise write workloads far beyond typical client or light server usage. In practical terms, this level of endurance means it can comfortably serve as a system or boot drive for many years under normal operating conditions, while also providing strong headroom for write-intensive applications. Its enterprise-grade reliability is further strengthened by power-loss protection (PLP), which helps preserve in-flight data and metadata during unexpected power interruptions, reducing the risk of corruption or incomplete writes. An UBER of 1.0E-17 and an MTBF of 2 million hours indicate an extremely low unrecoverable bit error rate and a robust long-term reliability profile, giving procurement teams greater confidence in data integrity and operational stability.

Technical Specs & Insights

1. The SAS 12Gb/s interface provides dual-port enterprise connectivity and broad server compatibility, making it ideal for highly available storage arrays and mission-critical infrastructure.
2. With 1200 MB/s sequential read performance, this drive accelerates large-block data access for backup, analytics, and media streaming workloads.
3. Delivering 190,000 K IOPS in random reads, it supports dense virtualization and database environments where fast response to many small requests is essential.
4. Rated for 3 DWPD, the SSD can sustain heavy daily write traffic over its service life, helping enterprises deploy it confidently in write-active applications.
5. Built on Samsung V-NAND 3bit MLC (TLC) and featuring 110 µs typical latency, it balances flash density with consistently quick access times for predictable application performance.

Capacity Sweet

For MPN MZILS400HEGR0D3, the nearest lower capacity in the same family is typically 200GB, and the next higher capacity is 800GB. In this series, sequential read/write performance and random IOPS are generally very close across these three capacities, which is standard for enterprise SSD product tiers. At 400GB, this model sits in the sweet spot of the lineup. Compared with the 200GB version, it gives noticeably better space headroom for OS images, logs, and application growth. Compared with the 800GB model, it usually delivers a more attractive cost-per-deployment while keeping essentially the same enterprise-class performance profile. It is well suited for medium-scale infrastructure, such as boot and cache storage for around 20 to 30 virtualization hosts or a compact mixed-workload database cluster.

FAQ