PCPer File Copy Test
Our custom PCPer-FC test does some fairly simple file creation and copy routines in order to test the storage system for speed. The script creates a set of files of varying sizes, times the creation process, then copies the same files to another partition on the same hard drive and times the copy process as well. There are four file patterns that we used to try and find any strong or weak points in the hardware: 10 files @ 1000 MB each, 100 files @ 100 MB each, 500 files @ 10 MB each and 1000 files at 1 MB each.
Creating and copying files should in theory bottleneck a given SSD at the bus bandwidth, but as you can see that's not the case. With our file creation test, things all come down to how a given SSD firmware has been optimized, and how that interacts with a command-line-based file creation tool. While the 840 still did well here, it is clearly more limited by write speeds – similar in fact to the write-limited Intel 320 Series.
The increase in program-erase times stacks up further when we force the 840 to perform those writes in parallel with reads from the same drive. Since the controller must complete service to each write operation, reads must also wait in line, which causes the effect to compound on performance, even though the 840 can read just as fast as the 840 Pro is capable.
Disclaimer: Our file copy test performs its copies with test files that contain repeating patterns and are therefore highly compressible. This gives SandForce-driven drives like the Vertex 3 and Intel 520 a bit of an unfair advantage.