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, which can result in a significant loss of write speed. Newer TLC drives use 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.


Write speeds start out at well over 2.5 GB/s, which is very impressive, and stay at that level until 150 GB have been written, which is the SLC cache size of the P34A80. Such a cache size is among the largest of the SSDs in our test group, which is great for soaking up large bursts of write activity. Once the SLC cache is exhausted, write speeds drop significantly, down to around 800 MB/s on average, but that's still is quite fast. On average, the P34A80 is one of the fastest SSDs we have ever reviewed when it comes to this test. Once write activity stops and the drive is idle, the pSLC cache gets flushed to TLC in the background and full write performance is restored.