Portable SSDs can offer amazing speed for content creation applications like transferring photo libraries or editing 4K video, but many suffer from a slowdown after prolonged use when their faster cache is depleted or the drive heats up too much. ProGrade has announced a new line of portable SSDs designed to address both of these issues: the PG10 Pro SSD.
Just like how good quality memory cards advertise burst and sustained write speeds, the PG10 offers similarly descriptive ratings. ProGrade specifies read and write speeds of up to 2,500 MB/s, with sustained write speeds of 1,500 MB/s for the 2 TB model and 2,000 MB/s for the 4 and 8 TB capacities. To enable these speeds, the drive features the blazing-fast USB 4.0 interface, which is also compatible with Thunderbolt 4 and 3, as well as USB 3.2 and 3.1 Type-C ports (although the slower USB 3.x implementations will prevent this drive from reaching those max speeds).
While these are solid specs for a USB 4.0 external SSD, the sustained speed aspect is what's really important. On some SSDs, the drive is designed to write to DRAM or a buffer of faster NAND memory first, then fall back to slower NAND if the write operation continues. In most consumer applications, this isn't noticeable, as you get the fast write for 5, 10, or more GB, and the operation concludes with the drive "flushing" that cache in the background. In other applications, like writing heavy 4K footage for a half hour, however, that initial cache is depleted, and write speeds fall sharply. While ProGrade hasn't provided additional details in the launch announcement about how they are handling this, they did show testing of the drive maintaining a 1.8 GB/s transfer rate even after writing to the drive for 46 minutes, drastically outperforming what they characterized as a "competitor SSD," which dropped after just 10 minutes.
The design is standard professional external SSD looks, although ProGrade has included some nice quality-of-life features with the drive: a power-sensing circuit and LED to inform users if the host device isn't providing the requisite 15 W, a magnetic base for drive stacking or workspace mounting via the included adhesive metal plate, and a hard-shell carrying case.
While I haven't been able to test the drive yet, I've worked with previous ProGrade products and found them to deliver on all the claims. These drives are really intended for power-users who are going to transfer hundreds of gigabytes or even terabytes of footage or files at a time, which is where you'll really notice the sustained write performance difference.
I use Prograde memory cards for photo and video and have never had an issue. That said, this is a pretty large hard drive in terms of size, and you can get away with something like the WD_BLACK 4TB SN850X NVMe Internal Gaming SSD Solid State Drive + ACASIS 40Gbps M.2 NVMe SSD Enclosure for likely a lot less than Prograde would charge and a much smaller form factor.
On these drives, it's all about that sustained write. A 1TB SN850X for instance has a cache depth of about 295GB, dropping got below 1Gbps after that.
They make good products, but the price is extremely high for what it offers. 2TB is $400, 4TB is $800, and 8TB is $1400
At those prices, you are looking at PCIe 4.0 U.2 based datacenter focused SSDs which tend to maintain their speeds from 0-100% (without the cache issues).
For higher end consumer SSDs, often the pSLC cache can be dumped to the TLC region while it is being written to (when not saturated), thus on slower interfaces such as many USB enclosures, often you will fill the drive long before you run out of cache (requires the SSD to also have a DRAM cache in addition to pSLC).
But even outside of cases like that, if you want to spend that kind of money for portable m.2 storage, then you could go with a USB 4/ 40Gbps enclosure (double the speed of the Prograde PG10), then get one of the higher end m.2 SSDs that will maintain a high enough speed to saturate the USB 4 connection even when the pSLC cache is filled. For example the Sabrent Rocket 5 2TB + a 40Gbps enclosure, will effectively give you ~4.5GB/s reads and writes (after overhead) from 0-100% fill, and the combo will still be cheaper than than the 2TB Prograde PG10 while being twice as fast.
(PS the Sabrent Rocket 5 2TB drops from about 12.7GB/s writes to 4.5GB/s when the pSLC cache is filled, though if bottlenecked by the interface, drives like that can clear the pSLC cache while handling solwer writes).