SATA HDD 8MB Cache vs. 16MB Cache?

Discussion in 'Mac Pro' started by TheSpaz, Jan 4, 2007.

  1. TheSpaz macrumors 604


    Jun 20, 2005
    I just picked up a new Western Digital SATA drive last night at Best Buy and it's the 250GB model but it costed a little more than the prices I saw online for it. Then, when I got home, I noticed that it has 16MB Cache and the drives that I saw online have only 8MB. I also noticed that the Mac Pro I bought came with the 8MB version. What is the difference/advantage of the 16MB cache vs. the 8MB?

    Also, should I be running the new 16MB cache drive as my boot drive since it has the spiffy 16MB Cache? (Whatever it means). Cause I can easily create a disk image of my current drive and copy it to the new one and swap places, then erase the 8MB Cache drive.

    I hope I'm making sense to y'all. I'm assuming that 16MB is faster than 8MB, so I'd probably want to run the faster one as my boot drive, no?
  2. shellbryson macrumors 6502


    Dec 28, 2006
    Larger cache will always help with performance, especially on a OS disc. Cache is basically an area of RAM in the drives electronics that temporarily stores files that have been written or read to the drive. Drives are slower than memory; it means if you are reading a file several times from disk, subsiqent reads may come from a cached copy rather than a disk copy, meaning much faster response. Also sometimes you get write caching - if the drive is very busy writing a file to disk and you ask it to write to another file at the same time, the drive can cache this write and defer it actually being written to disk until the disk is less busy - again speeds things up. A larger cache improves all disk access speeds.
  3. TheSpaz thread starter macrumors 604


    Jun 20, 2005
    Thanks! Last night I made a copy of my Startup Disk onto my new 16MB drive and booted with it this morning. It was a bit slow on startup but, that could just be from the computer using the drive as a boot disk for the first time. I'll test another startup when I get home.

    One quick question I have... Do I need to put the startup drive in Bay #1 or does it not matter?
  4. timb macrumors regular

    Jun 6, 2003
    Doesn't matter.

    I recently tested the stock Mac Pro 250 GB WD drive versus a Seagate Barracuda 7200.10 with 16 MB cache. They were about the same speed in the 2 GB file test (though the Seagate edged the WD out by about 10%), however on the multiple small file test (5 MB), the Seagate had a whopping 30% advantage!

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