Some models of SSD can’t save video data at the speed the manufacturer claims. This is due to the disk using hidden data compression to attain higher write speeds. This data compression can only save data at the manufacturer’s claimed speed when storing data such as blank data or simple files. Video data includes video noise and pixels which are more random so compression will not help, therefore revealing the true speed of the disk.
Some SSDs can have up to 50% lower write speed than the manufacturer’s claimed speed. So even though the disk specifications claim an SSD has speeds fast enough to handle video, in reality the disk isn’t fast enough when used to store video data for real time capture. However, this mostly affects HD capture and often these disks can still be used for playback.
Use Blackmagic Disk Speed Test to accurately measure whether your SSD will be able to handle uncompressed video capture and playback. Blackmagic Disk Speed Test uses data to simulate the storage of video so you get results similar to what you’ll see when capturing video to a disk. During Blackmagic testing, we have found newer, larger models of SSD and larger capacity SSDs are generally faster.