How much faster is the memory usually than the disk?

Question

IDE,SCSI,SSD,SATA or all of those.

Answer 1

I'm surprised: Figure 3 in the middle of this article, The Pathologies of Big Data, says that memory is only about 6 times faster when you're doing sequential access (350 Mvalues/sec for memory compared with 58 Mvalues/sec for disk); but it's about 100,000 times faster when you're doing random access.