Backing up 3tb iMac

Discussion in 'iMac' started by vaxes, Oct 24, 2013.

  1. vaxes macrumors newbie

    Joined:
    Sep 21, 2012
    #1
    Hi ive got a late 2012 iMac 3tb fusion drive (The first gen slim ones) before I upgrade to Mavericks i want to do a backup of my system.

    I currently have about 500gb of space left so I need a backup device that’s over 3tb.

    I was wondering what hard drives people use who are in a similar situation.

    I'm currently looking at LaCie d2 USB 3.0 4TB Thunderbolt External Hard Drive (http://www.amazon.co.uk/LaCie-Thund...+4TB+d2+USB+3.0+Thunderbolt+Series+Hard+Drive)

    has anyone used this drive? Is it any gd? A review on the apple store says they were only getting 46Mps???

    Thanks for any help
     
  2. Weaselboy Moderator

    Weaselboy

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    #2
    For a backup drive there really isn't any good reason to spend the extra money for a Thunderbolt drive. Just get a plain USB external in whatever size you need. Something like this Seagate drive would do the trick for you.
     
  3. talmy macrumors 601

    talmy

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    #3
    Even an old USB2 drive will do for this if you have the extra time (it will take about twice as long, I reckon.)
     
  4. rkaufmann87 macrumors 68000

    rkaufmann87

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    #4

    Lacie makes excellent solutions as does OWC (www.macsales.com). Because you have large amounts of data speed is important therefore I would urge you to use at a minimum USB 3 or Thunderbolt for the interface. Another possible vendor is G-Drive. All three vendors make high quality drives and enclosures. Do not go cheap on backup like many do, if your backup fails (don't laugh it happens every day) and your HD fails then you are up a creek. When it comes to backup, redundant backup is a very good idea.
     
  5. Bear macrumors G3

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    #5
    Actually 3 to 5 times longer than some USB 3.0 hard drives.
     
  6. load97 macrumors member

    load97

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  7. talmy macrumors 601

    talmy

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    #7
    Well I wouldn't run out and buy a USB3 drive just for a one-time full disk clone if I already had a USB2 drive. Just let it back up overnight.
     
  8. Bear macrumors G3

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    #8
    Presuming 3TB of data to copy, the best possible time you'll see for a USB 2 clone is about 17 hours. And that's presuming optimal conditions. And I was being generous in how fast USB 2 transfers disk data, so it'll probably be longer. That's not just overnight.

    So whether it's just a clone or a Time Machine backup, USB 3.0 is a very good idea. Especially if you consider they may have to restore data from the backup.
     
  9. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #10
    Absolutely correct. This isn't like the modest difference between a Haswell and Ivy Bridge CPU -- it's a huge difference. When you're dealing with 3TB of data, USB 2 isn't enough. I have 50 terabytes of documentary video data on many different external drives, and have tried all kinds of drives and interfaces. Depending on the variables, you may only achieve 20 MB/sec (sustained) on a USB 2 drive, which would be 41.6 hr for 3TB.

    Ideally you want a 7200 rpm USB 3 or Thunderbolt drive. It will have to be externally powered, as they don't yet make bus-powered 3 TB 7200 rpm drives.

    There is a 1TB 7200 rpm bus-powered USB 3 drive. I have several of these -- they are the fastest USB-powered drives I've found. For smaller backup needs they are very good: http://www.touropro.com/product/touro-mobile-pro/

    The previously-mentioned OWC 4TB drive looks good, but I don't have that.

    I have the 6TB WD MyBook Duo Thunderbolt. It's pretty quiet, not super-fast (despite RAID 0), but I've seen them for about $420. Using Carbon Copy, it sustains about 100MB/sec, which is about 1/2 the rated benchmark numbers you see. That is 8.3 hr for 3TB. When you must "get it done", the real world numbers are what count.
     
  10. Mobster1983 macrumors 6502

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    Sep 8, 2011
    #11
    I used a 3TB Seagate drive with USB 3 to back up the ~2Tbs on my 2013 iMac. I started Monday evening, and it didn't finish until Friday morning. Not sure what the issue was, but it was pretty frustrating having to wait four days to install mavericks.
     
  11. Bear macrumors G3

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    #12
    There's a USB issue you may have run in to. The iMac has 2 USB root hubs. Apparently if you have USB 2 devices plugged into a root hub or a hub hanging off the root hub, that root hub may operate as USB 2.0 speeds instead of USB 3.0 speeds.

    And the real issue is that some of the internal USB devices on an iMac may be USB 2.0 devices causing one root hub (2 ports) to be limited to USB 2.0 speeds. On a late 2009 iMac, the internal USB devices are:
    • Broadcom hub
    • Bluetooth adapter connected to the Broadcom Hub
    • SD Card Reader
    • iSight
    • IR Receiver
    The list may vary for other iMacs, but some of these devices in the current iMac could be slowing one of the USB buses in the iMac down.
     
  12. Brian Y macrumors 68040

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    Oct 21, 2012
    #13
    Do you encrypt backups? That makes it ridiculously slow for me.
     
  13. Bear macrumors G3

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    #14
    Encrypted Time Machine backups has minimal impact on backups. Other backup software that does its own encryption (not using HFS+ encrypted volumes) might have worse overhead for their encryption.
     
  14. joema2 macrumors 65816

    joema2

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    #15
    That is approximately 84 hours for 2TB, which works out to 6.6 megabytes/sec, which is very slow.

    USB 2 drives (esp 5400 rpm bus-powered ones) can be very slow when handling large data volumes.

    Speed of backup also depends on the backup software. I use Carbon Copy, which is very fast, but it is also limited by the underlying hardware speed.

    Bear's comment about USB hubs is interesting. On my 2013 iMac 27, I tested a Carbon Copy backup to a bus-powered 7200 rpm USB 3 drive, both with and without another USB 2 device in a port.

    I got about 62 megabytes/sec averaged over 5 min. whether or not an adjacent USB 2 port was in use.

    However that's on a 2013 iMac 27; it's possible older or different models have the USB 2 behavior Bear mentioned. Note: all iOS devices are USB 2. If this behavior exists on any iMac, simply having an iPhone plugged in might cause it.

    Regardless, a sustained backup rate of 6.6 megabytes/sec is way too slow.

    A quick Google query shows some other people complaining about that Seagate drive.

    As a first pass, I'd suggest reformatting it, unplug all other USB devices from your iMac, reboot, then try another backup. You need not back up the entire amount to assess the backup rate, assuming the backup software gives a progress and quantity indication.
     
  15. Bear macrumors G3

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    #16
    Unless they changed something in the 2012/2103 models, Ports 1 and 3 are on one USB root hub and ports 2 and 4 are on the other USB root hub.

    Also what is not know is if matters what order the devices are plugged in. Try plugging in the USB 2 device first.
     
  16. joema2 macrumors 65816

    joema2

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    #17
    Thanks. I tried a USB 2 device in port 1 and the USB 3 device in port 3; on my system it made no difference in throughput.

    I also re-ran the below tests with a USB 2 device in port 1. This is on a 2013 iMac 27, 3.5Ghz i7, 32GB RAM, 3TB Fusion drive, OS X 10.9. All external drives formatted HFS+.

    Carbon Copy 3.5.3 backup; source disk: 2013 iMac 3TB Fusion Drive. Target disk: below. Data rate is the 5 min average after start:

    Fantom 2TB USB 2.0 (AC-powered): 45.6 MB/sec
    Hitachi Touro 1 TB USB 3.0 (bus-powered): 61.9 MB/sec
    Toshiba Canvio 1 TB USB 3.0 (bus-powered): 66.3 MB/sec
    Buffalo DDR 3TB USB 3.0 (AC-powered): 87.4 MB/sec
    Fantom 2TB USB 3.0 (AC-powered): 87.0 MB/sec
    WD Mybook Thunderbolt Duo 6TB RAID 0 (AC-powered, Thunderbolt interface): 87.6 MB/sec

    My 8TB Pegasus R4 RAID 5 disk is tied up doing a re-sync right now. When that gets done (sometime tomorrow) I'll run the above backup test on it.
     
  17. talmy macrumors 601

    talmy

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    #18
    Thanks for running the tests. It verifies my conjecture in the third post that USB2 will take about twice as long as USB3. USB3 is limited by the speed of the drive, not the connection technology. I don't understand why the RAID 0 Thunderbolt drive is so slow.
     
  18. joema2 macrumors 65816

    joema2

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    #19
    I've seen many cases on Windows where USB 3 is 3x faster than USB 2. You just never know; there are many variables but USB 3 in general is a lot faster.

    The MyBook Thunderbolt Duo is simply not a fast RAID 0 drive. It uses 5400 rpm drives and is designed around lower cost and lower acoustic noise. It does about 280 megabytes/sec in the BlackMagic and QuickBench benchmarks. The above data rate is using Carbon Copy which has its own I/O profile, largely dependent on the disk structure it's backing up.

    For large reads, the 3TB Fusion drive read rate is at least 2x that fast and the Pegasus R4 in RAID 5 about 3x that fast.

    The bottom line is just don't use USB 2 for backup, likewise don't use it if you regularly transfer large amounts of data from high-def camcorders, DSLRs, etc.

    Of course a USB 3 reader or disk drive will be slow on a computer with USB 2 ports. As data volumes increase the difference is so dramatic it's worth replacing the entire computer just to get USB 3.
     
  19. luffytubby macrumors 6502a

    luffytubby

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    Jan 22, 2008
    #20
    As a long term investment, I think it doesn't get better than this. If money is no object you could go for 8 TB.

    Remember, it's great to have the extra space!
     
  20. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #21
    One more piece of data. This is on Windows 7, but it is using the same drives I tested on Mac OS X.

    I was doing a drive-to-drive copy of 1.7TB from a 2TB USB 3, 7200 RPM, AC-powered Fantom drive to an identical drive having both USB 2 and eSATA interfaces.

    Using the USB 2 interface on the target drive, data transfer was 30 megabytes/sec. It was the weakest link in the chain.

    Switching to the eSATA interface (maintaining the USB 3 interface on the source drive), the data rate increased to 110 megabytes/sec. The much faster eSATA interface on the target drive allowed the USB 3 source drive to perform at a higher rate.

    This clearly shows that USB 3 is much faster than USB 2. It also shows that in a sequential transfer, no matter how fast all other system components are, the slowest element will constrain overall speed.

    I/O interfaces like this make a much larger real-world impact than whether or not you're running a Haswell CPU.
     

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