One and a half years after the release of the 860 QVO (test), Samsung launched the 870 QVO, the successor to the retail market: The 2.5-inch SSD is the first consumer Sata model with a capacity of up to 8 TB. QVO stands for Quality and Value Optimized – a slightly euphemistic name for a product that should convince with a very low price per gigabyte.
In fact, the previous 860 QVO is one of the cheapest Sata SSDs with a capacity of 1 TB to 4 TB, only the very slow Crucial BX100 and a few older models cost even less. Unlike the 860 Evo, the 860 QVO is already available for 200 euros instead of 300 euros if we compare 2 TB versions. The 860 QVO and also the 870 QVO – which is supposed to start at similar prices – are not so cheaply available for a reason.
Both SSD series use 3D flash memory with 4-bit cells, also known as Quad Level Cells (QLC). To save data, 16 charge states are necessary, which means correspondingly complex write processes. On the one hand, this results in a low data rate when information is written directly in QLC mode, and on the other hand it wears out the memory cells more if only eight (triple level cell) or four (multi level cell) instead of 16 charge states are used.
Inside there are controllers, DRAM and two packages on the front and one on the back. (Image: Marc Sauter / Golem.de)
Samsung uses the V-NAND v5 with 96 cell layers for the 870 QVO, the older V-NAND v4 is still used for the 860 QVO. According to the South Koreans, the new 3D flash memory is at least fundamentally faster due to a DDR4 instead of a DDR3 toggle interface and should nevertheless have the same energy efficiency thanks to finer manufacturing. Samsung uses multiple 1 TBit QLC dies for the 870 QVO, eight of which are in one package. Our 4 TB pattern shows four such chip cases. The V-NAND v5 is controlled by the eight-channel MKX controller, which accesses LPDDR4X memory as a DRAM cache for the mapping table and supports AES-256 hardware encryption.
To keep the write speed high, Samsung operates part of the QLC memory in SLC mode, i.e. with one bit or four charge states. As with the 860 QVO, the 870 QVO also has a minimal buffer that can be expanded dynamically depending on the level of the SSD. With the 1 TB model, this amounts to 6 GB and can dynamically add up to 36 GB for a total of 42 GB SLC buffer. As soon as less than 168 GB (4x 42 GB) are available on the SSD, the dynamic cache is gradually reduced until only 6 GB can be used.
|870 QVO (1 TByte)||870 QVO (2 TByte)||870 QVO (4 TByte)||870 QVO (8 TByte)|
|Controller||MKX, 8 channels||MKX, 8 channels||MKX, 8 channels||MKX, 8 channels|
|DRAM cache||1 GB LPDDR4||2 GB LPDDR4||4 GB LPDDR4||8 GB LPDDR4|
|NAND packages||1 x (8 x 1 TBit, 96L)||2 x (8 x 1 TBit, 96L)||4 x (8 x 1 TBit, 96L)||8 x (8 x 1 TBit, 96L)|
|SLC Turbowrite||6 + 36 GB||6 + 72 GB||6 + 72 GB||6 + 72 GB|
|Seq. Read||Up to 560 MB / s||Up to 560 MB / s||Up to 560 MB / s||Up to 560 MB / s|
|Seq. Write||Up to 530 MB / s||Up to 530 MB / s||Up to 530 MB / s||Up to 530 MB / s|
|Write without TW||Up to 80 MB / s||Up to 160 MB / s||Up to 160 MB / s||Up to 160 MB / s|
|TBW||360 TB||720 TB||1,440 TB||2,880 TB|
Samsung 870 QVO data
With the SLC buffer, the 870 QVO writes sequentially at up to 530 MByte / s, nasty copying processes under Windows 10 run at 480 MByte / s. As soon as the cache is exhausted, the data transfer rate drops to 80 MB / s (1 TB model) or to 160 MB / s (2 TB to 8 TB). That is as much as the older 860 QVO with 130 MByte / s. The 870 QVO has slight advantages in input / output operations per second when using a very short command queue (QD1). At the maximum sequential write and read rates of 560 MByte / s and 530 MByte / s, no differences between the two QVO SSDs can be determined.
Samsung will sell the 870 QVO with 1 TB (117 euros) from the end of June 2020. The models with 2 TB (234 euros) and 4 TB (468 euros) are to follow at the end of July, with 8 TB (848 euros) from the end of August . They are more expensive than the 860 QVO currently, but prices are likely to settle down. The South Koreans give another three-year guarantee, and the TWB durability (Terabytes Written) corresponds to that of the previous QLC SSD.
The 870 QVO is the logical further development of its predecessor: a Sata SSD in 2.5-inch format, which has a lot of QLC storage space per euro and is primarily designed for read access. The Samsung drive is less designed for continuous writing processes, although the dynamic SLC buffer with up to 78 GB is quite decent; after that it is only 160 MByte / s. If you want to use the 870 QVO as an SSD for game libraries or photo archives without exorbitantly large RAWs, you can access it.