[lars]

A few years ago I made a (non-interactive) visualization similar to this, that made its way to hackernews [1]. It puts this on a linear scale, so you can get a feel for the baffling difference between your most local caches and your hard drive:

http://i.imgur.com/X1Hi1.gif

Note: This is a huge gif, zoom in to the top.

[1] HN discussion: http://news.ycombinator.com/item?id=702713

[yahelc]

How does a SSD compare?

[whalesalad]

I had a crazy thought recently that I need to test:

If you had your swap partition set to a raid array of SSD's. Like two 64GB inexpensive SSD drives... I wonder how it would perform compared to RAM.

[vidarh]

The limitation with a decent RAID array of SSD drives will be your controller and/or your PCI interface. I have servers at work we get ca. 1200MB/sec reads from without any real tuning, while we get ca. 6000MB/sec from a RAM disk (which of course then still costs us the overhead of the filesystem layer). You might be able to beat that with a suitably designed setup, but it's likely to be expensive.

Getting 500-600MB/sec is "cheap". Getting 1200MB/sec gets a bit pricy but isn't hard (the setups we've tested "just" involved us popping 4x OCZ Vertex drives of various models into a server with SATA III, without much regard for anything else).