Western Digital has upped the bus connect from PCIe gen 3 to gen 4 for its Blue 500 series internal SSD, increasing speed by between 20-70 percent.
Blue drives are for desktops and notebooks not needing the highest performance (its Black brand drives provide that). The SN570 used the PCIe gen 3 bus and is an internal fit M.2 2280 finger-length SSD card using BiCs 5 112-layer 3D NAND in 3bits/cell (TLC) format. The drive was fitted with an SLC (1bit/cell) cache and had no onboard DRAM, needing a host memory buffer. It was launched in October 2021 and Western Digital has now updated it with a PCIe gen 4 bus connect, twice as fast as PCIe gen 3, but still using the same BiCS 5 112-layer 3D NAND.
There has been no formal announcement by Western Digital but the drive specs have appeared on its website.
Capacities are unchanged at 250GB, 500GB, 1TB and 2TB. So too are the endurance numbers over the 5-year warranty period. This means 150TB written for the entry-level 250GB product, 300TBW for the 500GB variant, 600TBW at the 1TB capacity level and 900TBW for the 2TB product. The mean time to failure (MTTF) rating has improved, though, from the SN570’s 1 million hours to the SN580’s 1.5 million hours.
Speeds, detailed in the product brief, vary with capacity:
For comparison the SN570’s speeds at the 1TB capacity point were:
- Random read IOPS: 460,000
- Random write IOPS: 450,000
- Sequential read: 3.5GBps
- Sequential write: 3GBps
The SN580 is around half as fast overall as the SN570. It has a later version of WD’s nCache technology, the use of an SLC (1bit/cell) cache to speed writes and lower TLC write amplification. This v4 nCache provides faster file copies – “blistering fast” is Western Digital’s term, but no actual numbers are provided.
There are faster PCIe gen 4 M.2 drives such as Western Digital’s own Black SN770, which runs at up to 740,000/800,000 random read/write IOPs, and has a 5.1GBps and 4.9GBps max sequential read and write bandwidth rating. But it costs a little more.
The SN580 drive draws 65mW when active and 3.3mW when in sleep mode. The Amazon prices are $27.99 for the 250GB model, $31.99 for the 500GB, $49.99 for 1TB, and the 2TB retails at $109.99.
For comparison, the Black SN770’s Amazon prices are $79.99 for 1TB, $134.98 for 2TB, and $184.98 for 4TB.
Bootnote
Western Digital’s nCache technology uses a combination of both SLC (single level cell) and TLC flash blocks to improve endurance, efficiency, and performance. By writing data to the SLC cache first, write amplification on the TLC blocks is decreased. The SN580 uses the SLC cache for file copying.
