Does using USB hard drive for Time Machine slow down the iMac?

Discussion in 'macOS' started by HXGuy, Aug 26, 2010.

  1. HXGuy macrumors 68000

    Mar 25, 2010
    Just finished setting up my new 27" iMac and the last piece of the puzzle is to setup Time Machine. I have an external 500GB hard drive that Im not using (even though my hard drive is 1TB, Im only using 157GB right now so the 500GB should be fine).

    My concern is...will it slow down the computer when its backing up since the drive is USB? Would it be worth buying a Firewire 800 external drive (~$150)?
  2. spinnerlys Guest


    Sep 7, 2008
    forlod bygningen
    It will not slow down the computer, even though the CPU is used for communicating with USB devices. The initial backup will take a while though, but subsequent backups should be fast.
  3. MrCheeto macrumors 68030


    Nov 2, 2008
    Your computer will slow down, slightly, but that's just because your internal hard drive is busy trying to read all of your information to copy it.

    This is inherent and there isn't a way around it. I can't say FireWire would be much faster, if at all.

    Time Machine will format whatever partition you choose to use as your Time Machine partition, so be certain you create a Time Machine partition manually, first, to save the other data.

    Click on the link to my blog in my signature. I explain how it works and how it's set up.
  4. HXGuy thread starter macrumors 68000

    Mar 25, 2010
    Maybe I should have been patient and read that before I started? :D

    On the 500GB drive, I was already using 150GB for some video and I left that on there. When I started Time Machine, it asked which drive I want to use and showed the external drive with 350GB available, so I chose that...didn't do any other portioning. Should be fine, right?

    As for the speed thing...I know it can slow down the system every so slightly (especially on the initial backup) concern was more do with USB vs Firewire hard drives and if it's worth buying a Firewire drive to use with Time Machine.
  5. MrCheeto macrumors 68030


    Nov 2, 2008
    Hm, pür hapz it doesn't re-partition if the drive is already Mac OS X Extended (Journaled)...
  6. TheBritishBloke macrumors 68030


    Jul 21, 2009
    United Kingdom
    I believe with a FW800 drive you'll be getting ~70% more performance in regards to transfer speeds (800Mbit/s as Opposed to 480Mbit/s)
  7. HXGuy thread starter macrumors 68000

    Mar 25, 2010
    Yea, that's what I'm reading, that FW 800 is around 70% faster than USB2.0.

    The question is, will it really affect anything or be noticeable with using Time Machine (not factoring in the initial back up)?

    And yes, the external drive was already OSX Extended Journaled.
  8. mulo macrumors 68020


    Aug 22, 2010
    Behind you
    well actually, the faster your backup drive is the faster your backups will be, but the harder it will impact performance since the computer needs to devote more resources to the backup. even then I take backups on a FW800 and i do this while playing world of warcraft or starcraft 2 and all is fine, cant notice it

    so all in all the only difference is going to be how long it takes to backup
  9. Angelo95210 macrumors 6502a


    Jan 7, 2009
    Paris, France
    I noticed that when a disk wake up it slows down your computer. After that when the backup is started is fine and nearly unnoticeable but still it consumes resources this is why I prefer to switch on the backup drive and launch my TM backup manually.
  10. Stealthipad macrumors 68040


    Apr 30, 2010
    If it does it does not slow mine down any more as all three of my time machines died after only a few months of service. No more for me!

Share This Page