What do I need to get USB3 speed?

Discussion in 'Mac Basics and Help' started by doubledee, May 30, 2013.

  1. doubledee macrumors 6502

    doubledee

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    Location:
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    #1
    If I bought an External HDD Enclosure like this...

    OWC Mercury On-The-Go™ Pro USB 3.0 Portable Enclosure Kit

    ...then would that mean that I would get "USB3 speed" between the enclosure and my new cMBP??

    Or do I need a special kind of Conventional HDD to attain that?

    (I just bought a 2.5" 750GB Seagate HDD last month, but it is in my car in a box, and I have no clue how fast it is, other than it is 7200rpm...)

    Sincerely,


    Debbie
     
  2. SnowLeopard2008 macrumors 604

    SnowLeopard2008

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    #2
    A platter HD will not saturate USB 3.0. An SSD will. USB 3.0 has a max bitrate (read: speed) of 5 gigabits/second. That is 0.625 gigabytes/second or 625 megabytes/second. A platter HD is lucky to get around ~100 megabytes/second. Remember, bits and bytes are different. 8 bits = 1 byte. Of course, that 5 gigabits/second figure is never achieve in real world. But it gives you an idea that the bottleneck is the platter HD, not the connector.
     
  3. doubledee thread starter macrumors 6502

    doubledee

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    #3
    So I hear you saying that a USB3 connection is roughly 5 times as fast as a conventional HDD, right?


    Then let me ask this...

    In an old thread of mine about creating clones, some said, "Make sure you don't try and boot your clone from a USB2 External Enclosure because they are really slow. You should buy a USB3 external enclosure instead!!"

    I'm sorta lost here...

    You are saying USB3 is way faster than the HDD.

    Then what about USB2?

    And is what that person said true?

    Do I really need to go out and buy a USB3 enclosure in case I need to boot my clone from it?!

    Sincerely,


    Debbie
     
  4. SnowLeopard2008 macrumors 604

    SnowLeopard2008

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    #4
    Yes, that is correct. That is to say, the slowest component is the platter-based hard drive, not your USB 3 connection. In comparison, a USB 2 connection has a maximum bitrate of 480 megabits/second. That is 60 megabytes/second. But in real world, you usually can't achieve that figure (I estimate 70-80% of the max bitrate in real world). So while the hard drive can reach ~100 megabytes/second in real world, the USB 2 connection can't go that fast.

    You really don't need USB 3 to be able to boot from your clone. It's just that anything you do will take longer to do on a USB 2 hard drive versus USB 3. You can boot using either USB 2 or 3, but USB 3 will let you get things done quicker. It's like driving a car. Speed limit is 60-65 mph on freeway (in the US at least) but your car's maximum velocity is usually over 100 mph. So the slowest component is the speed limit. The car is analogous to hard drive. Speed limit is analogous to USB 2 connection.
     
  5. doubledee thread starter macrumors 6502

    doubledee

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    #5
    Since the purpose of a clone - at least to me - is to serve as a *temporary* fix while you sort out a bad HDD or corrupted Op Sys, then USB2 vs USB3 probably isn't that big of a deal, right?

    And my objective is just to have something that serves the same purpose as the "Recovery DVDs" back "in the good ol days"... :cool:

    I just always want a copy of Mountain Lion and related Apps, so if I have to rebuild my laptop/HDD, I have something handy.

    (I am not planning on working from a Bootable HDD - just using it to *restore* things...)

    Sincerely,


    Debbie
     
  6. SnowLeopard2008 macrumors 604

    SnowLeopard2008

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    #6
    It depends. Actively using the OS that is on a USB 2 connection will lag because there isn't enough bandwidth to remove said lag. USB 3 won't lag. If you don't care, then there isn't a difference.

    For a "recovery dvd", just create a bootable installer USB drive. Directions below.

    http://arstechnica.com/apple/2012/07/how-to-create-a-bootable-backup-mountain-lion-install-disk/

    As for bundled apps, it's really just iLife that isn't in the bare OS. I think it's a good compromise since most likely that isn't your biggest concern.
     
  7. doubledee thread starter macrumors 6502

    doubledee

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    #7
    Is there any benefit to going through the hassle of downloading Mountain Lion from Apple's website and making a "Recovery Disk" on a USB drive, versus using something like CCC to create a "clone" of my new cMBP and having that serve as the "Recovery Disk" on a USB drive??

    (I guess I am kinda fuzzy on what the end difference really is?!) :confused:

    Sincerely,


    Debbie
     
  8. SnowLeopard2008 macrumors 604

    SnowLeopard2008

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    #8
    There really isn't much difference in the end, save that downloading ML from Apple and putting that on a USB drive will NOT include iLife. You will have to download iLife separately.
     
  9. doubledee thread starter macrumors 6502

    doubledee

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    #9
    I don't even know what iLife is?! (Guess that isn't an issue?!) *LOL*

    Thanks,


    Debbie
     
  10. SnowLeopard2008 macrumors 604

    SnowLeopard2008

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    #10
    iLife suite of applications are iMovie, Garageband and iPhoto.

    It comes pre-installed on every Mac. But the OS itself does not include iLife. So by cloning your new MBP's hard drive, you get iLife. But downloading ML from Apple will not included iLife.
     
  11. chown33 macrumors 604

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    #11
    After you make the clone on the USB drive, you'll likely keep it somewhere fairly close at hand. For example, in a desk drawer in your house. If your internet connection is down or slow at the time you need to reinstall, then the clone is instantly available (or however long it takes to get it from the desk drawer), but a remote reinstall is not.

    FWIW, you can also clone the HD to an SD card (or a microSD card in an adapter), and that will also be bootable. I've done it, and it's slower than USB2. My impression is that it's slower than a conventional hard disk, but I didn't run benchmarks; it's just an impression. So I only suggest this if there are other overwhelming reasons for choosing SD or microSD (cheaper, physically smaller).

    I should also note that USB3 flash drives are not all equally fast. I've had good results with the ADATA S102 models, in 16 and 32 GB sizes. YMMV.
     
  12. Weaselboy Moderator

    Weaselboy

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    #12
    That won't work for doubledee, since she did not buy Mt. Lion from the app store so she won't have the installer file.

    There is a work around though. You can snag the installer from Apple using this process (it works for Mt. Lion also), then use this free app and a 8GB USB key to make an installer.

    doubledee >> I don't want to derail this thread... but I posted some questions in your other thread about what exactly you are trying to accomplish with an installer/clone.

    ----------

    SL2008 is right on target. Good, recent article here showing file transfer speeds on USB 2/3 with both hard drive and SSDs.
     
  13. doubledee thread starter macrumors 6502

    doubledee

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    #13
    I looked at this link and saw...

    "Downloading" WHAT, from WHERE?! (I thought the idea of doing all of that was to capture what was on the Mac Recovery Partition versus *downloading* from Apple?!)

    Also, why does it say "Lion" and not "Mountain Lion"??


    No worries.

    I check out what you have to say in that thread in a moment!



    Interesting article. Thanks!

    Sincerely,


    Debbie
     
  14. Weaselboy Moderator

    Weaselboy

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    #14
    Okay... let's clear something up that I think is a misunderstanding from your Windows days. The OS X installer is not on your hard drive and is not on the Mac Recovery HD partition. All that is on that partition is some troubleshooting tools and a stub that allows you to DL the actual OS from Apple. The Recovery HD partition is only 650MB and does not contain the OS like some Windows machines do.

    So what you are downloading is the 4.7GB OS installer and it needs your password to complete that DL.

    The article says Lion instead of Mt. Lion because that article was written when Lion came out, but the same process works now with Mt. Lion. If you want to make yourself a USB key Mt. Lion installer without having to pay again for Mt. Lion from the App Store, this is the only way to do it.
     
  15. doubledee thread starter macrumors 6502

    doubledee

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    #15
    "I see!!" said the Blind Man!! :p

    (Yeah, I wasn't getting that?!)


    After spending $1,500 I'm not crazy about spending another $20, but the twenty bucks is NOT my concern.

    My concern - which I thought you saw in this or my other thread - is the whole DOWNLOADING issue (i.e. Security over wireless connections while away from home).

    I was talking about this same issue in this thread...


    Another idea is this...

    5.) Go to the Public Library and use WiTopia to download Mountain Lion
    (fairly secure + free = fairly good)

    (The Library should be less likely to have hackers, and in reality, I am paying $50 for WiTopia because it should keep me safe over *any* connection as long as there isn't someone sitting next to me with one of those Alfa jammers...)


    But as I said in the other thread, just having the factory HDD from my cMBP is probably more than enough for my needs. (Assuming that HDD survives in my car!!)


    Somewhere today someone told me that I could also use CCC to make a Bootable Clone on a USB Thumbdrive...

    So - assuming that was true - then I could get everything I want, and without having to download anything, right??

    Sincerely,


    Debbie
     
  16. SnowLeopard2008 macrumors 604

    SnowLeopard2008

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    #16
    This is a little bit unclear. I'm not really sure what you mean myself.
     
  17. Weaselboy Moderator

    Weaselboy

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    #17
    If you go to the Apple Store today and buy a new Macbook and bring it home and login then look in the previous purchases in the App Store application, you will not see Mountain Lion on the list since you never bought it from the App Store. So if you want to get your hands on the 4.7GB installer DMG, you have two choices.... you can pay the $20 to buy it from the App Store or you can grab it from Apple's Servers during the recovery process (free) as described in the article.

    What happens is when you start recovery like that the system sends your machine's serial number to Apple's servers and the servers see that serial number is entitled to Mountain Lion free since it came with the machine... so the servers send down the Mountain Lion installer. What is happening in that article is we are stopping the install after the DMG is downloaded and before the installer launches.

    This is different than say a 2009 Macbook that came with Snow Leopard and you upgraded to Mountain Lion through the App Store. If you run recovery on that machine, Apple's servers would see the serial number is not entitled to the free Mountain Lion installer and you would be asked to enter the AppleID used to purchase Mountain Lion to proceed with the download.

    You are not the first person to be a bit confused by all this. IMO Apple has not done a very good job explaining it.
     
  18. Weaselboy Moderator

    Weaselboy

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    #18
    The point is you would do this DL while at home and put the installer on the USB key. No download would be required in the field after that.
     

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