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Toshiba BG4 1TB SSD Review

The BG4, Toshiba's fourth generation ball grid array (BGA) drive, is a tiny SSD – basically not that much bigger than a NAND package, or just a bit smaller than a standard SD flash card. It's possible for the drive to be made this small because the controller and flash are combined in a single package. An OEM part at present, Toshiba are aiming the  BG4 at ultra-mobile and 2-in-1 notebook PCs, IoT/embedded devices and as boot drives for server and storage arrays.

The drive uses Toshiba's latest 96-layer BiCS4 3D TLC NAND and a new PCIe 3 x4 controller. This is a large leap forward from the previous BG2 and BG3 models which used 64-layer NAND and a PCIe 3 x2 controller. Despite its small size the BG4 comes in four capacities; 128GB, 256GB, 512GB and 1TB and in two formats – surface mounted M.2 1620 or module mounted M.2 2230.

When it comes to Sequential performance, the official figures for the 1TB drive are rated at up to 2,300MB/s for reads and up to 1,800MB/s for writes. Both of those figures we were able to confirm using the ATTO benchmark, with the review drive producing read figures of 2,422MB/s and writes of 1,879MB/s.

The 4K random performance, on the other hand, was disappointing. The official maximum 4K random read figure is rated at up to 390,000 IOPS, but the best we could get out of the drive was 247,013 IOPS. Write performance was even worse, the best figure we got from our 4-threaded test was 77,132 IOPS – nowhere close to the official rating of up to 200,000 IOPS.

That aside, we think it is still amazing that a drive this small can not only have up to 1TB in capacity but also have Sequential read/write speeds of 2,300MB/s and 1,800MB/s respectively. 4K random performance isn't great, but the BG4 provides the opportunity for manufacturers of ultra-portables and other very small format systems to install some fast storage.


  • Compact size.
  • Sequential performance.


  • OEM part only at present.
  • Tested 4K performance was disappointing.

KitGuru says: Although an OEM part, the BG4 may well find its way to the consumer space in the not too distant future.

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Rating: 8.0.

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