Hard Drive File I/O Help

This is a discussion on Hard Drive File I/O Help within the Tech Board forums, part of the Community Boards category; I'm pretty ignorant about many computer hardware topics. I've been banging my head against this for a couple of days, ...

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    Hard Drive File I/O Help

    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?
    If I did your homework for you, then you might pass your class without learning how to write a program like this. Then you might graduate and get your degree without learning how to write a program like this. You might become a professional programmer without knowing how to write a program like this. Someday you might work on a project with me without knowing how to write a program like this. Then I would have to do you serious bodily harm. - Jack Klein

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    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?
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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    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.
    If I did your homework for you, then you might pass your class without learning how to write a program like this. Then you might graduate and get your degree without learning how to write a program like this. You might become a professional programmer without knowing how to write a program like this. Someday you might work on a project with me without knowing how to write a program like this. Then I would have to do you serious bodily harm. - Jack Klein

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