Imac 2017 with Samsung T3 as main drive

Discussion in 'iMac' started by psmichaelgunawan, Jul 29, 2017.

  1. psmichaelgunawan macrumors newbie

    Jul 29, 2017
    Hi everyone. I'm new to this forum and this is my first post.

    I just bought a new 2017 iMac with kaby lake and it is the mid tier one. I bought it from the Apple Store and I just realised that I didn't have the SSD and had the 1 TB Fusion drive.

    I am afraid that the Fusion drive make my iMac be a stepdown from my 2012 MBP Retina which had SSD and be much slower.

    I am thinking of buying a Samsung T3 External SSD and set it as the Main boot drive to make it as fast as my MBP. I will then stick it on the back of the iMac. Is this a possible solution? Please do help me.
  2. EugW macrumors 603


    Jun 18, 2017

    As for your idea. Well, it's a bad idea. The Samsung T3 over USB has no TRIM support, and even ignoring the TRIM aspect, it's also simply much slower than an internal Apple SSD. And of course, it's just a clunky solution for a brand new machine.

    I would recommend returning the iMac and buying one with an SSD.
  3. psmichaelgunawan thread starter macrumors newbie

    Jul 29, 2017
    Thanks for the reply. I can't return it as I bought it overseas and the store won't accept refunds. What do you suggest I do?
  4. EugW macrumors 603


    Jun 18, 2017
    Honestly, I don't know. Unfortunately, you bought the worst of the Fusion drives. The 1 TB Fusion drive only has a 32 GB SSD. The 2 TB and 3 TB Fusion drives have a 128 GB SSD included.

    You could try running it to see how it performs, but honestly I think you just bought the wrong machine. It will be OK for lighter usage, but with some stuff you may end up getting noticeable slowdowns.

    However, if you really want to go with an external drive, you could use Thunderbolt 3. It's more expensive, but you'll get TRIM.

    In a pinch, a T3 will work, but it's a suboptimal and clunky solution. I would have suggested that for say a 2012 iMac, but it just doesn't make a lot of sense for a brand new 2017 iMac.
  5. psmichaelgunawan thread starter macrumors newbie

    Jul 29, 2017
    True. I bought it on an impulse. I dont know what I should do now. So will this imac be that slow compared to my macbook pro?
  6. EugW macrumors 603


    Jun 18, 2017
    Initially it may be fine, but it will slow with time as your drive fills up. I don't know how fast your MBP is though.
  7. MikeArtworks macrumors regular

    Jun 1, 2015
    Quick question to you @EugW . Do you have a hard time transitioning from the iMac to the Macbook, as you go from 27 inch to 12 inch (when on the go I presume). Is it not a too big of a difference?
  8. propower macrumors 6502a

    Jul 23, 2010
    The current 2017 iMac internal SSD is super fast (2500+/2000+ r/w).Much as i agree that the Fusion is a serious downgrade from an internal SSD I also think you should experiment a little and see how that goes. The SSD part of the Fusion does help at least.

    If that is not doing it for you - it is most likely a big improvement to boot from a straight USB3 SSD (expect ~350MB/s Read and write). Next step up is the T3 (430/400 r/w). Even better is to get a true USB 3.1 Gen2 (has to be Gen 2) external case (that plugs into one of the TB3 ports on your iMac) and put your own SSD in it (Samsung 850 Evo or Pro). This should give you full speed from an external SSD (~550MB/s Read and ~450MB/s Write). I wish I could recommend a case for you but I have not had any experience yet with them though I am looking at Akitio and Oyen (hopefully others can help).
  9. OldMike macrumors 6502


    Mar 3, 2009
    Dallas, TX
    Ok, I am going to have to go against the grain here and disagree. I think running the iMac from an external drive is a very workable solution.

    For the past 4 years I have been running off of external SSDs in my Macs without a hitch. Performance and stability have been excellent. I don't have experience with the T3, but I can tell you that I have had multiple Mac Minis running off of this external USB3 enclosure:

    Granted, its not the nicest looking enclosure but it has been 100% reliable. Uptime is measured in time between forced reboots for OS updates. With Samsung 850 EVO 512GB and 1TB SSD drives speeds are 450MB/s. Are they as fast as Apple's internal SSD drives? Of course not. Could you tell a difference, not as much as you might believe. When I format these drives, I leave 10% unformatted, which helps with garbage collection since TRIM is not supported. I can almost guarantee that even without TRIM, these drives will last longer than your system will.

    If you are afraid running an external would be 'clunky' then I would opt for something like this Twelve South storage shelf:

    If you are surprised about my comment regarding external drives running at 450 MB/s compared to ultra fast internal SSDs, take a look at this article:

    In that article they tested Samsung 960 EVO SSD drives with max throughput of 3200 MB/s read and 1500 MB/s write. Performance comparison between that fast SSD vs an 850 EVO SSD with read/write speeds of about 500 MB/s in real world terms are as follows:

    Windows 8.1 Boot time:
    Samsung 960 EVO ~ 15.3 seconds
    Samsung 850 EVO ~ 15.5 seconds

    790 MB 4K video load time:
    Samsung 960 EVO ~ 6.5 seconds
    Samsung 850 EVO ~ 6.5 seconds

    523 MB GIMP image load time:
    Samsung 960 EVO ~ 8.3 seconds
    Samsung 850 EVO ~ 8.5 seconds

    159 MB Project opened in Visual Studio containing source code for LLVM toolchain:
    Samsung 960 EVO ~ 6.5 seconds
    Samsung 850 EVO ~ 6.5 seconds

    Ok, now I realize that these drives were not Apple SSDs, but were instead Samsung 960 NVMe drives. But we are talking about the difference between drives that are getting an actual 2,000 MB/s read times vs drives that get 500 MB/s read time. And the difference in real world usage is not detectable. Running off of USB3 will cause a slight performance penalty, but not enough to make a difference.

    I say go for running external. I can't vouch for the Samsung T3 since I do not have experience - but I will say that I have had very positive experiences running off of external drives for a long time (including HDD before SSDs came onto the scene).

    Personally, on my next Mac purchase I am going into it knowing that I will most likely be using the internal drive as a scratch drive or backup drive, and plan on running exclusively on an external SSD. I like the fact that if there is an issue with the drive or I want to boot my system on a different Mac, it is plug and play. If I can get an external Thunderbolt 3 enclosure for a good price, I would be very open to switching to that - but otherwise running off of an external USB3 drive with UASP support works very well!

    That is my take....
  10. nambuccaheadsau macrumors 68000


    Oct 19, 2007
    Nambucca Heads Australia
    1. Sell it and cut your losses.

    2. No matter what you do you are never going to be satisfied with the machine.
  11. EugW macrumors 603


    Jun 18, 2017
    Yes, it works OK, and I've done it myself, but it's to breathe life into an old non-SSD Mac. To have to do this on a brand new 2017 iMac is real shame though.

    It's a huge difference, but they serve different purposes of course.

    At home I actually use dual 27" iMacs with one of them acting as a second screen. On the road it's just one 12" screen.

    At home I find having just one screen a bit restrictive. On the road I find even my old 13" MacBook Pro too big and awkward. However, on the road I'm mostly in office and business applications, and just deal with the small screen. If I find I need more, I do it at home on my dual iMac setup. My photo library is only managed on my iMacs.

    Some people prefer something in between to handle both jobs (such as a MBP 15" with external screen at home), but that's not me. I prefer two separate setups.
  12. Fishrrman macrumors P6


    Feb 20, 2009
    OP wrote:
    "What do you suggest I do?"

    Download the BlackMagic speed test utility if you don't have it.
    Run it on your iMac and post the results here.

    I wouldn't go with some of the nonsense posted above.
    If it runs well enough, use it.

    You might wait a while until USB-c 3.1 Gen2 external drives hit the market.
    One of those would make a very speedy "external booter" for the iMac...
  13. SaSaSushi, Jul 31, 2017
    Last edited: Jul 31, 2017

    SaSaSushi macrumors 601


    Aug 8, 2007
    Takamatsu, Japan
    Excellent advice. You could also get an $85 Delock TB1 enclosure and an SSD with an Apple TB3 to TB2 adapter. It is a great device. I'm using mine for Bootcamp now.
  14. joelpagan macrumors newbie


    Jun 18, 2017
    I had a similar conundrum:

    Anecdotally, running the OS off of an external SSD (Samsung T3 in this case) was substantially faster than the internal Fusion in almost every case. The 28GB SSD portion of the Fusion drive is just too tiny to store much of anything, and any parallel processes would bog down to a frustrating level (especially relative to the fact that its a brand new, higher-end computer in 2017). The T3 based solution did not do this and was much more snappy on average.

    In the end, I wound up returning the base iMac for one a high tier machine, with a 2TB Fusion drive and higher end graphics, and I split the fusion drive into a 128gb SSD (OS / Apps) and 2TB scratch / storage / bootcamp drive. I also used my T3 SSD as the storage for my home folder, for documents and for apps I don't use often.

    I needed a machine quickly or I would've built to order and replaced the fusion with an all SSD internal solution and added storage via TB3 as needed.

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