WD Black SN850 2TB vs Samsung 980 Pro 2TB

Read speed

This is the maximum sequential read speed according to the manufacturer. High sequential read speeds are most useful when the system is reading very large files (such as videos) from the SSD.

This is the maximum random read speed according to the manufacturer. It is measured in IOPS (Input/Output Operations Per Second) and is a good indication of the read performance of the SSD in day-to-day usage.

Write speed

This is the maximum sequential write speed according to the manufacturer. High sequential write speeds are most useful when the system is writing very large files (such as videos) to the SSD.

This is the maximum random write speed according to the manufacturer. It is measured in IOPS (Input/Output Operations Per Second) and is a good indication of the write performance of the SSD in day-to-day usage.

Benchmarks

The sequential write speed benchmark gives an indication of the SSD performance when writing large files. The value given here is the average result calculated from user-submitted scores. Source: UserBenchmark.

The sequential read speed benchmark gives an indication of the SSD performance when reading large files. The value given here is the average result calculated from user-submitted scores. Source: UserBenchmark.

The random write speed benchmark gives an indication of the everyday performance of the SSD. The value given here is the average result calculated from user-submitted scores. Source: UserBenchmark.

The random read speed benchmark gives an indication of the everyday performance of the SSD. The value given here is the average result calculated from user-submitted scores. Source: UserBenchmark.

The PassMark benchmark measures the overall performance of the SSD based on read speeds, write speeds, and seek times. The value given is an average based on user-submitted results.

General info

SSDs with a DRAM cache utilise high-speed RAM as a cache. This results in higher performance than DRAM-less SSDs, which use a slower NAND cache or the system’s RAM (HMB).

NVMe SSDs use the PCIe interface, which has a higher bandwidth than the SATA interface. This results in much faster read/write speeds compared to SSDs which use the SATA interface.

The internal storage refers to the built-in storage space available in a device for system data, apps, and user-generated data. With a large amount of internal storage, you can save more files and apps on your device.

The storage type determines how many bits of data are written to each memory cell. These storage types include SLC (one bit per cell), MLC (two bits per cell), and TLC (three bits per cell). The less bits that are written to each cell, the greater the speed and reliability.

Peripheral Component Interconnect Express (PCIe) is a high-speed interface standard for connecting components, such as graphics cards and SSDs, to a motherboard. Newer versions can support more bandwidth and deliver better performance.

The controller is a processor that manages the functions of the SSD. The number of channels refers to the number of storage chips that this controller can access at once. Typically speaking, the more channels that the SSD controller has, the greater the performance.

Terabytes Written (TBW) is a measurement of the SSD's endurance, and often refers to the manufacturer's warranty. A higher TBW can be an indication of greater reliability over time.

MTBF (Mean Time Between Failures) is the manufacturer’s estimation of the average time for a device to fail.