Write Intensive Usage

When copying games from your Steam Library or other very large files (>10 GB), you might have noticed that write speeds on your SSD start out at full speed and then drop considerably. The underlying reason is that modern drives have caches that soak up write bursts to improve performance. In the fairly uncommon scenario of writing data that's too big to fit into these caches, the drive will have to write data directly to flash, and it will probably juggle some out of its write cache at the same time as well, which can result in a significant loss of write speed. Newer TLC drives operate part of their capacity in SLC mode for increased performance. This test can reveal the size of that SLC cache.

Testing on this page looks at exactly that scenario. We write a sequential stream of 1 MB blocks to the drive in a single thread, like a typical file-copy operation would do, and measure write speeds twice a second. The drive is fully erased before testing to ensure any caches are emptied. Please note that this test writes a lot of data in a very short time, which is something most consumers will never do.


Our synthetic testing showed the Samsung 970 Pro as powerhouse when it comes to write performance, so we were really curious about the results for this test. With 2100 MB/s average sustained write performance, the 970 Pro is the fastest drive we have thus far come across in this scenario. While write speeds do drop a little bit from time to time, the drops are not nearly as significant as on drives with TLC. Very impressive.