Time Machine restore and physical placement of files on the disk

Discussion in 'macOS' started by tlindaas, Oct 28, 2009.

  1. tlindaas macrumors newbie

    Joined:
    Mar 15, 2008
    #1
    When installling OS X I always try to cluster the OS related files at the outer tracks of the hard drive, where the disk is fastest. (See http://macperformanceguide.com/Storage-WhyYouNeedMoreThanYouNeed.html)
    So I generally like to install OS X to an empty hard drive, and be done with all the OS related updates before I go on to install applications, copy user files etc. Most of the OS related files (depending on need for future updates) will now be clustered nicely together, making the machine as fast as it can be.

    My question is: Does Time Machine "respect my efforts" here when doing a full restore? Will it place my system files at the outer tracks where they belong, or will it ignore the original placement of the files?

    Thanks!
     
  2. mreg376 macrumors 6502a

    Joined:
    Mar 23, 2008
    Location:
    Brooklyn, NY
    #2
    Interesting. I haven't heard of this strategy being used since the days of clunky hard drives. I doubt that Time Machine addresses this at all, since with current hard drives you'd probably need a lab bench to discern any speed differences.
     
  3. tlindaas thread starter macrumors newbie

    Joined:
    Mar 15, 2008
    #3
    I think it is the same now as before. Take a look at the link, they use 1.5 tb disks to show the difference.
     
  4. gnasher729 macrumors P6

    gnasher729

    Joined:
    Nov 25, 2005
    #4
    You don't need a lab at all. On a modern hard drive, read/write speed on the outer tracks will be about twice as fast than read/write speed on the inner tracks. That is one reason for buying a bigger hard drive than you need; 160 GB on a 500 GB drive will use the outer, faster tracks only, while 160 GB on a 160 GB drive will also have to use the inner, slower tracks. It is also a reason not to trust any hard drive benchmarks unless the benchmarker really knows what they are doing.

    Time Machine is very unlikely to have explicit code that attempts to restore to the outer tracks, but the operating system will do that automatically; it will always allocate space at the outer tracks first when creating new files.
     
  5. mreg376 macrumors 6502a

    Joined:
    Mar 23, 2008
    Location:
    Brooklyn, NY
    #5
    Yes, the tests. But I'd like you to take 10 identical Macs, five of which have had OSX installed as you describe, and five which haven't, randomize them, and then load and use an application of your choice on each. I'd be curious how successful you'd be identifying which was which.
     
  6. robbieduncan Moderator emeritus

    robbieduncan

    Joined:
    Jul 24, 2002
    Location:
    London
    #6
    I'm pretty sure it won't (at least not intentionally/by design, it might be accident/luck).
     
  7. mreg376 macrumors 6502a

    Joined:
    Mar 23, 2008
    Location:
    Brooklyn, NY
    #7
    But what you're talking about is a difference of milliseconds. And with modern CPU caches and OSX memory management, that difference will often be masked anyway. My point is that today these speed differentials are insignificant unless you're designing the wing of the new Boeing 787.
     
  8. tlindaas thread starter macrumors newbie

    Joined:
    Mar 15, 2008
    #8
    Wouldn't the difference between installing the OS on the outermost vs the innermost tracks be like having a disk that is 50-100% faster than your previous disk? Since the outermost tracks are roughly twice as fast as the innermost tracks? CPU cache and memory managment should be the same for the outer and inner tracks?
     

Share This Page