5k iMac -> Monster Fusion Drive with 1tb SSD?

Discussion in 'iMac' started by sammyman, Sep 21, 2016.

  1. sammyman macrumors 6502a

    Mar 21, 2005
    Is it possible to create a monster fusion drive on a new 5k iMac?

    i purchased a 1tb Apple SSD for my 2010 Mac Pro. I also have a 6tb WD drive. I'm wondering if I could get a base model 5k 27" iMac and upgrade the hard drives? Then throw in some RAM. Would love to use the parts I have.

    But can you have a 7TB fusion drive? Or will Apple limit you? Also, will I only be able to do this with an iMac that was setup with Fusion? Or could I get the base 1tb hard drive model?
  2. varian55zx macrumors 6502a


    May 10, 2012
    San Francisco
    Can't imagine why you'd want that.

    Pure flash will always be superior.

    Just move your media files onto the HDDs and keep your system files on the SSD.
  3. sammyman thread starter macrumors 6502a

    Mar 21, 2005
    I just have the drives sitting around. I guess the 6tb can go external.

    So should I buy the cheapest 2015 1tb or 1tb fusion, remove and then install my 1tb ssd. Would that work?
  4. ApfelKuchen macrumors 68030

    Aug 28, 2012
    Between the coasts
    No reason to not want it. Who cares if pure SSD is "superior?" Sure it is, by about 10%-15%, for whatever is resident on the SSD. But the spinning HDD will always run at spinning HDD speeds - roughly 20% of the speed of the SSD. I'd call 20% grossly inferior.

    This person has a choice - a zero-maintenance 7TB Fusion drive running at 80-90% of the speed of an SSD, or a 1TB SSD and a separate 6TB HDD, where the user has to actively manage which materials will benefit from SSD and which don't.

    And as to "System files on the SSD, data on HDD..." System requires around 6-7GB. Not many people have 993-994GB of apps. So, what's the point of that whopping big SSD? It'll likely be 20-30% full, 70-80% waste. Once the OS kernel and key modules of an app are loaded into RAM, the SSD would pretty much sit idle.

    Meantime, OS and apps are worthless without data. This whole, "data can be slow" thing is total crap. We work with data all day long. So, why should every data read/write run at a fraction of the speed of that SSD? True, there are some data types that are only read once, written never (media files, for example), so they may load no more quickly under Fusion than from pure HDD. But if the same data is hit again? Fusion will have moved it to SSD (with no user intervention), and all subsequent hits will run at SSD speeds.

    Now, as far as the question of whether OS X will create a Fusion drive from that setup... I believe that it will, but I don't have the specifics of how to do it in front of me. I suspect that, if you have another use for a 1TB SSD, you may get better value from it in that alternate use. Unless you're using a substantial proportion of that 7TB of storage on a very regular basis, you may detect no performance difference between Fusion with a 250GB SSD and a 1TB SSD. But only you know how you use your system. Huge, frequently-accessed data sets most likely could benefit (let's say if 500GB of the data is accessed frequently), but the kind of data I use... no way.
  5. varian55zx macrumors 6502a


    May 10, 2012
    San Francisco

    Since when did caring about things being better than other things go out of style?

    To each their own, but I've owned both so I've been there done that.

    I found the fusion to slow down the more you fill it.

    That's why I'll be getting a pure SSD in my late 2016 iMac when it comes out.
  6. MadDane macrumors 6502a

    Apr 5, 2015
    AFAIK there are a couple of different connectors/versions of the Apple SSD. Assuming you have the one that fits in the 2015 iMac then yes, it should work.
  7. Fishrrman macrumors P6


    Feb 20, 2009
    I agree with above opinions, in that trying to create a huge fusion drive using a 1tb SSD makes no sense at all.

  8. maflynn Moderator


    Staff Member

    May 3, 2009
    I see no reason to do that imo. If I had a 1TB SSD, I'd be very happy with the performance, why sacrifice that with a slower drive. Fusion was created to give near SSD speeds at a hard drive price point.

    Since the OP already shelled out the $$ for a large SSD, making a Fusion drive out of it, would be superfluous imo
  9. sammyman thread starter macrumors 6502a

    Mar 21, 2005
    So now I just need to confirm if it will fit in the new 2015 or 2016 iMacs.....

    I'll get researching.

    I could also sell it and spend that money towards a ssd directly from Apple. That may be the best idea.
  10. danielwsmithee macrumors 65816

    Mar 12, 2005
    I don't see any problem at all with a very large Fusion drive with a 1TB SSD. Sure once you go past the 1TB SDD things will slow down dramatically for the remaining 6TB. That is just the nature of a Fusion Drive and unless you have the money for a 7TB SSD I don't see any problem with it theoretically.

    I would actually be much more interested in a Fusion based iMac if you had the option of upgrading the SSD from 128 GB to something larger say 512GB or 1TB.

    All that being said I'm not a big fan of opening and replacing a brand new iMac, or with storing 6TB of data on a single drive. Sure you can have a backup of the drive, but the pain of restoring 6TB of data makes it worth creating a raid in my opinion anyways.
  11. sammyman thread starter macrumors 6502a

    Mar 21, 2005
    Looks like the 1tb drives still cost about the same when I bought it maybe a year ago. I'm just sell it on eBay and then get the apple 1tb iMac so I don't have to hassle with opening and replacing it myself.

    Thanks for all the input.
  12. steve23094 macrumors 68020


    Apr 23, 2013
    Can you Fusion an internal an external drive together?
  13. danielwsmithee macrumors 65816

    Mar 12, 2005
    Yes you can, but if the external drive is not connected you won't be able to use the internal drive which is why most people don't do it.

    You can even create fusions from RAIDs and RAIDs from Fusion drives.

    My 2009 iMac has been upgraded to a 128GB SSD with the OS, and a 960GB SSD for the user accounts. That setup works pretty well.

    I'm thinking of creating a fusion drive by:

    Partitioning the 960GB drive into 128GB and 832 GB partitions.

    Then creating a RAID-0 set from the 128GB drive and 128GB partition from the 960GB drive.

    From that creating a Fusion from the 256GB Raid-0 set and the 832GB partition.

    That should give me a 1088 GB Drive drive where the first 256 GB has the performance of RAID-0 set of SSDs, and the next 832 GB has the performance of single SSD.

    I'm going to wait until I get a new one before doing this to the old one and use as second computer for my kids homework so it will be an experiment as much as anything else. Ultimately these SSDs are running at half their performance potential right now because the 2009 iMac has SATA2 ports.
  14. mpe, Sep 26, 2016
    Last edited: Sep 26, 2016

    mpe macrumors 6502

    Sep 3, 2010
    No, it won't be superior. If you plan to organise data between SSD and HDD, then fusion drive will be faster in many situations. SSD isn't just for system files. In fact I want to have SSD primarily for my data.

    If it is only for media library then you might not notice, but it could matter for many other things. it is unlikely that by organising data manually, you'll outsmart the algorithm. Most likely everything will be more HDD like experience that if you were using FD.

    I actually plan to fuse 512GB SSD and 6TB HDD for the very same reason.

    Not necessarily. Obviously even if you get past 1TB the CoreStorage will still continue promote/demote data based on LRU. Unless you have a very specific workload it is very unlikely that with 1TB of cache you'll ever get HDD speeds...
  15. varian55zx macrumors 6502a


    May 10, 2012
    San Francisco
    How incredible.

    You're really trying to tell me that an equivalent flash setup with the same amount of storage wouldn't be superior?

    How absurd!!!

    You should educate yourself on the actual advantages of flash over HDD. Flash is superior in every conceivable way by a wide margin.
  16. danielwsmithee macrumors 65816

    Mar 12, 2005
    Except for cost of course.
  17. mpe macrumors 6502

    Sep 3, 2010
    I agree with you that SSD is magnitude faster, but you quite likely don't understand my point.

    What I say is that if you fuse SSD and HDD, it will be in many situations much faster than if you put SSD for your system files and keep managing data on HDD manually.

    caching is an old technique that isn't perfect, but still tremendously effective.
  18. varian55zx macrumors 6502a


    May 10, 2012
    San Francisco
    This is something I have seen mentioned and a much more reasonable claim than "flash just isn't superior".

    I think this is debatable. I had a 2tb fusion on my iMac and I split it, I found it be noticeably faster split and I kept it split and preferred it.

    My organization was impeccable, though, including a sophisticated use of aliases going back to the HDD but to each his own. I preferred it split.
  19. mpe macrumors 6502

    Sep 3, 2010
    Well, I can argue against your preference, but if you split your data you'll be experiencing HDD performance every time you'll be accessing data that are located on HDD. No exception.

    If you were using fused drive then there is a good chance that vast majority of reads and all writes < 4GB would be cached from SSD depending on how exactly you use your data. CoreStorage would effectively hide HDD latencies for you'd have more SSD experience than with two separate volumes.

    Symlinks between SSD and HDD volumes can be very tricky. Often they can bring HDD latencies back to your system (imaging stating a folder on your SSD with symlinks to HDD when HDD goes to power save mode). If you were using FD, then these would just live on your SSD

    I wish there was affordable 2,3,4,5,6 TB+ pure SSD for me. But until then large fused SSD + huge HDD is the second best option.
  20. varian55zx macrumors 6502a


    May 10, 2012
    San Francisco
    True. However, when I had the two split, I'll tell you what I had on the HDD.

    - documents
    - video files for TV shows
    - music files

    That's it. So in that instance it doesn't matter that that stuff is on the HDD, I would assume a speed decrease isn't even noticeable.

    In respect to everything I know about this subject, keeping your music files on your HDD vs SSD shouldn't incur any major speed difference.

    So I wouldn't want them on the SSD portion of my fusion drive then, it's taking up space that is better taken up by other things. So that's why I split it, I wanted control over what goes where.

    The lack of control in the fusion setup is somewhat annoying to me.

    I'll be getting the 512 or equivalent option in my new iMac anyway.
  21. mpe macrumors 6502

    Sep 3, 2010
    I certainly don't want my documents on HDD. I want them on SSD. Especially those fresh I am working on right now. As for video/music files, maybe they can live on HDD, but I would prefer to have those part of files with headers and metadata on the SSD, so that I can quickly index them and go through them. I also want to write any new files to SSD first in order not to be waiting for HDD. Core storage works on block level rather than file level, so it can guarantee that. When you are managing files manually, aren't you frustrated by the fact that you don't have that level of control?

    The lack of control is more obsession than anything else. You can easily spent more times managing files and thinking about how to organise your volume than if you let the software do it for you.

    I don't say that fused volumes are perfect at everything, there are definitely use cases that are not suitable for them (such as huge databases or RAW video editing), but it works well for vast majority of applications.

    Also 512GB SSD is way to small for me, as only my Lightroom catalogue is over 1TB. I could probably squeeze my stuff to 1TB SSD when pressed, especially since that is the only NVMe unit in the line-up right now, but even that would be painful.

    I think particularly situation of people with media library is perfect application for fusion drive (even the basic one with 128GB SSD portion).
  22. varian55zx macrumors 6502a


    May 10, 2012
    San Francisco
    This is funny.

    At least I'll know how fast my computer is compared to yours when I'm enjoying 2000 mb/s read and write.

    You have fun with that.
  23. EnderBeta macrumors 6502a


    Aug 5, 2016
    With this kind of budget why not make it two 1TB SSD drives?

    When my iMac's AppleCare expires I'm going to crack it open and install the largest SATA3 SSD I can into it to go along with the 1TB PCIe SSD already in it.
  24. danielwsmithee macrumors 65816

    Mar 12, 2005
    A Fusion drive pairing a 1TB PCIe SSD with a 2TB SATA SSD would be a very nice setup.

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23 September 21, 2016