When trying to choose a SATA magnetic hard drive (not SSD) for high performance for both random and linear access, which should be the primary factor?
For example: would a 10k RPM drive with 16MB of cache perform better than a 7200RPM drive with 32MB of cache
Best Answer
The short answer is yes. Your total hard drive latency is the [seek latency] + [rotation latency].
The 10K RPM drive will have a smaller rotational latency due to its faster spinning and will also be able to read data off of the drive faster. What the higher cache will do is for writes. A cache is similar to a buffer. When it reads data from the disk it will store recently accessed data and data within the near vicinity for quicker access. This is called temporal and spatial locality. The higher cache will be useful if your access pattern is such that you read the same file a lot or the data is stored near each other.
Wikipedia has a decent page on disk caches.