Hard Drive File I/O Help

[pianorain]

I'm pretty ignorant about many computer hardware topics. I've been banging my head against this for a couple of days, and then I figured I should ask people who might be able to help.

At a previous place of employment, I wrote a program that read from a file cache holding a large data object (2-4 GB). The program was multi-threaded and so would read from different locations in this cache at different times. The file I/O was very non-sequential. In running the program on my development machine, the bottleneck was the file I/O due to the threads competing over the physical location of the hard drive head.

The program was deployed on a server machine, and the file I/O problem suddenly disappeared. The server had only a single hard drive, so it wasn't using RAID. The hard drive was not a SSD. I'm looking to purchase a server machine with this same characteristic, but I don't know what could have been responsible for this behavior. Any suggestions?

[Salem]

Server machines tend to have lots of RAM.
Also, since they're not running a multitude of user programs, more of that RAM can be permanently committed to cache.

> The program was multi-threaded and so would read from different locations in this cache at different times
How many real cores does each machine have?

[pianorain]

The development machine had two. The server machine had eight.

The server did have a lot of RAM, but I don't think much of it was committed to hard drive caching. Most of it was used by the program I described above.