Released in 2020, the Samsung PM981a is a solid-state drive in the M.2 2280 form factor available in 256 GB, 512GB, and 1 TB capacities. When it comes to connectivity, the Samsung PM981a utilizes a PCI-Express 3.0 x4 connection and features the NVMe (non-volatile memory express) protocol in version 1.3.
The PM981a is largely an OEM version of the Samsung 970 EVO Plus optimized for higher efficiency. It is primarily used in a variety of laptops from e.g. Asus, Lenovo, HP, and Dell.
The SSD controller used is the Phoenix (S4LR020) from Samsung, which is paired with an on-board DRAM cache for enhanced performance. In terms of NAND storage technology, Samsung has utilized 92-layer V-NAND V5 TLC flash chips in the PM981a (unlike the original 970 EVO, which used the previous-gen V4 NAND). It is however worth noting that different variants of this SSD are available, featuring different NAND flash or controller versions, which may impact performance.
The PM981a makes the most of its PCIe 3.0 connection and offers sequential read speeds of up to 3,500 MB/s and write speeds of up to 3,000 MB/s. 3,500 MB/s is about the highest possible throughput possible via a PCI-Express 3.0 x4 connection, in practical terms.
In terms of random IO performance, it achieves 580K IOPS for read operations and 550K IOPS for write operations (1TB capacity). This is in line with high-end SSDs from the same generation. To optimize write speeds, the Samsung PM981a employs a pseudo-SLC cache, enabling it to handle bursts of incoming writes more efficiently. This cache has a capacity of 42 GB, and once it reaches its full capacity, write speeds are reduced to about 1700 MB/s.
Specifications
| Samsung PM981a Specifications | 256 GB | 512 GB | 1 TB |
|---|---|---|---|
| Interface/ Protocol | PCIe 3.0 x4 NVMe 1.3 | ||
| Form Factor | M.2 2280 (Single-Sided) | ||
| Controller | Samsung Phoenix (S4LR020) 8 Channels | ||
| NAND | 92-Layer TLC (Samsung V-NAND V5) | ||
| Overprovisioning | 17.6 GB (7.4%) | 35.2 GB (7.4%) | 70.3 GB (7.4%) |
| DRAM | 512 MB LPDDR4-1866 | 1 GB LPDDR4-1866 | |
| Encryption | AES-256 TCG Opal | ||
| Sequential Read Performance | 3,500 MB/s | ||
| Sequential Write Performance | 2,200 MB/s | 2,900 MB/s | 3,000 MB/s |
| Random Read Performance | 240K IOPS | 460K IOPS | 580K IOPS |
| Random Write Performance | 480K IOPS | 500K IOPS | 550K IOPS |
| SLC Write Cache | 12 GB | 22 GB | 42 GB |
| Endurance | 150 TBW | 300 TBW | 600 TBW |
| Warranty | 5 Years | ||
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