About ready to order 27" iMac to fusion or not

Discussion in 'iMac' started by kuau, Dec 3, 2012.

  1. macrumors newbie

    Dec 3, 2012
    I am about ready to put my order in for the new 2012 iMac 27"
    Going for 3.4GHz Quad-core Intel Core i7
    8GB RAM, will upgrade to 32GB via OWC.

    I just can't decide on which drive setup to order.
    I am initially thinking the 1TB Fusion setup, then disable Fusion, install OS/APPS on the 128GB Flash Drive and use the 1Tb drive for iTunes storage.
    Then use both, a external USB3 4TB Drive for image storage and a 256GB SSD Thunderbolt for Lightroom 4 Catalog and PS6 scratch disk.
    and one more USB3 4TB for backup timemachine.

    Will this work? Meaning disabling Fusion, creating 2 separate volumes, install Lion on the SSD, and go from there?

    I have nothing against Fusion, but I am still worry that if the 1TB HD dies, then so does my iMac, I have much more faith in SSD/Flash drive then a spinning HD..
  2. macrumors 6502

    Feb 24, 2010
    that's nonsense, do not pay $250 for fusion just to disable it and use the ssd + hdd separately :confused: I dont know why you are so worried about hdd failure despite what you read or experienced they are rare.

    The whole point of fusion and paying $250 is to have a good working solution that balances performance with storage space.

    If you are this OCD about the 1TB hdd failing, then dont order fusion and get an external thunderbolt ssd like the lacie and install everything on there.

    Btw despite no moving parts and lower power consumption, ssd can fail just as much as hdd...

  3. macrumors 601

    Jun 29, 2010
    Lmao why would you get a Fusion Drive then disable it? :eek:
  4. macrumors 6502a


    Nov 6, 2003
    Because he wants to control what's on the SSD.

    It's a reasonable desire, IMO. I'm just not sure it's possible.
  5. macrumors 601

    Jun 29, 2010
    I thought you could choose if you wanted something on the SSD part :eek::(
  6. thread starter macrumors newbie

    Dec 3, 2012
    Good points from everyone.
    I guess if keep my fusion storage to under 100GB it will never hit the spinning drive.

    I guess what scares me is fusion reminds me of a raid 0 setup, works great until one of the drives fail.

    Please correct me if I am wrong though, if the Flash drive dies, or the HD dies, do I still have working iMac if it's configured as fusion?

    I guess another option is a 256GB SSD Thunderbolt drive, boot from that OS and Apps, purchase the 3TB version of the iMac and use the internal drive for time Machine..
  7. macrumors 65816


    Mar 5, 2003
    Seattle, WA
    Definitely get the Fusion drive, and don't mess with managing the storage yourself, that's what the Fusion drive does. It's like people who try and manage their music and photos on their own instead of just letting iTunes and iPhoto do it.
  8. hfg
    macrumors 68030


    Dec 1, 2006
    Cedar Rapids, IA. USA
    Get the Fusion drive and don't worry about failure, just keep a reasonable backup as you should anyway.

    A fusion drive failing is no different than a non-fusion OS drive failing. And, yes, a RAID-0 works great until one of the disks fails, but a single drive also works great until the drive fails. *** BACKUP ***

    To answer your direct question however ... yes you can break the fusion join and revert the drives back to normal SSD and Hard Disk ... but I wouldn't do that, I would enjoy the Fusion experience. Doing so will require a couple of Unix commands in Terminal, you can't do it from the Disk Utility GUI.
  9. macrumors 603


    Aug 5, 2010
    That is a very expensive method of obtaining an ssd scratch disk. 32GB of ram might be enough to hold things in ram with seldom scratch disk use, even on larger images with lightroom in the background. You must remember that the concept of the scratch disk, which acts as a dedicated page file, originated when ram was sold in terms of megabytes. The need for scratch disk performance is not as high as it was for the majority of this kind of work with the falling cost of ram.
  10. macrumors 6502a


    Nov 6, 2003
    Except for the expectation that the rate of failure for a Fusion drive will be greater than either a SSD or a mechanical drive on their own. This is because the probability of failure is additive for two independant events: Pfail(Fusion) = Pfail(SSD) + Pfail(HDD) - Pfail(SSD and HHD).

    So by using a fusion drive you are opening yourself up to greater risk of failure and data loss. In any case, you should have redundant backup systems anyway, so hopefully a Fusion drive failure is not much more serious than an annoyance.

    Still, you should be aware of the risk.
  11. macrumors 68030


    Oct 6, 2008
    It is much safer than raid 0, as no files are split between drives, it is either one or the other. If the HDD dies you should still be able to boot.

    If you just keep a backup of the whole thing though I don't know what you have to worry about...
  12. macrumors 604

    Mar 29, 2008
    Wha? That's news to me. I was under the impression it's the same likelihood of failure as a RAID0 array, i.e. if EITHER drive fails, the whole partition is dead.

    Quick google search:

    "Reliability: with the Fusion drive, if either drive goes south then the system dies. Two drives will be less reliable than one drive, end of story. "

  13. hfg
    macrumors 68030


    Dec 1, 2006
    Cedar Rapids, IA. USA
    I don't think that is quite true ... the block nature of the Fusion operation may well have some contiguous files which are partly on one drive and partly on the other.

    However, I suspect that the frequency of usage would, in fact, keep the boot related files entirely on the SSD and could possibly successfully perform a boot. Where it would leave you after that would be interesting. I have seen nothing indicating that any files are purposely "pinned" to the SSD other than through access frequency.

    A factory fresh new machine will be delivered with everything on the SSD simply because that is how it loads the disks and everything in the oem distribution will fit on the SSD.

    But as you said, keep a good backup to restore the "drive", be it RAID-0 or Fusion, once the failed drive is replaced and the drives rejoined and formatted. Same thing with a single drive OS that fails ... replace the drive, format, and restore from backup.
  14. macrumors 68040

    Aug 9, 2009
    Portland, OR
    I agree that the concern about reliability is being overblown. That is why you have backup. With a good backup plan... losing a drive is a non-issue.

    I do think there are usages where manually managing where data resides (OSX, certain applications, certain application data) is valuable. What the OP is suggesting is that this is a $250 option to get his OS, Applications.. and limited other data permanently (and manually) onto the SSD. The only other 'off-the-shelf' currently available option is the $1300 full SSD model.

  15. macrumors 603


    Apr 13, 2010

    This is fully true with the advent of t-bolt and usb3 external clones of the fusion drive will be fast and work as a booter. op was talking about a lot of coin to spend on his externals.

    he should look into this


    just clone the internal fusion drive once a week with ccc or superduper.
  16. macrumors member

    Jun 13, 2012
    I'll trust iTunes simply because there is nothing better, but iPhoto... no thank you. For any robust file management apart from import-and-never-touch I'll stick to Lightroom and the likes.
  17. macrumors 65816


    Mar 5, 2003
    Seattle, WA
    Different strokes for different folks. I've used them all and I prefer the way iPhoto handles things. I don't care where the originals are as long as I can get to them easily and they are backed up.
  18. macrumors 604


    Mar 29, 2011
    SSDs are really as likely to fail as HDDs? Why? I thought they were less prone to failure? What fails about them? Memory corruption? :eek:
  19. macrumors member

    Sep 1, 2012
    ssd has limited read/write capabilities.

    example OCZ Vertex 3 Max IOPS 120GB, 2.5", SATA 6Gb/s has
    Random 4K read: 35000IOPS • Random 4K write: 75000IOPS

    IOPS = Input/Output Operations Per Second


    Also found this article:

    A 2011 study by Intel on the use of 45,000 SSDs reported an annualized failure rate of 0.61% for SSDs, compared with 4.85% for HDDs. "Link". Intel. July 2011. Retrieved 10 February 2012.
  20. macrumors 603

    Feb 20, 2009
    "I guess what scares me is fusion reminds me of a raid 0 setup, works great until one of the drives fail.
    Please correct me if I am wrong though, if the Flash drive dies, or the HD dies, do I still have working iMac if it's configured as fusion?"

    I've seen little yet as to how a user deals with a fusion drive failure, either a software failure or in hardware.

    I'd reckon that if you have the two drives "fused", when either fails, you lose the entire "drive".

    Perhaps the only solution is to keep a cloned backup (NOT a Time Machine backup), so that you can boot from that in a moment of need.

    Since the iMac is going to be difficult to open and repair (at least for 90+% of users), simply replacing either the internal SSD or HDD won't be easy, either. It -may- be possible to use Disk Utility [booted externally] to re-initialize the "remaining drive" to then use as a "normal" (i.e., non-fused) drive, and "let the dead drive lay" where it is.

    I have no problems managing different drives and partitions -- I have no less than *8* drive icons on the right side of my display as I type this. I know where things are and -prefer- to keep my volumes and files "separated".

    If you don't mind managing two (or more) volumes or partitions, I see NO advantage to having a fusion setup -- NONE.

    Also, there would be no problems ordering a fusion drive and then "de-fusing" it -- fusion, per se, is a concept in software, not hardware. When the customer buys a fusion drive, all he/she is getting are two individual drives with the fusion capabilities enabled through software.

    I myself won't even bother with an internal SSD. I'll pick up a "bare" SSD cheap, and use it with either a standalone case or perhaps even in a USB3/SATA dock. The boot time may be a bit longer than if the drive were mounted internally, but probably no more than 30 seconds -- who cares? Once up and running, I doubt that there will be little perceivable difference in app launch times, etc.
  21. macrumors 601

    Jun 29, 2010
    I am curious soon to be Fusion owner here, do you recommend keeping a HUGE iTunes music collection on a seperate partition? I am coming over from PC and had it set up this way incase the OS partition went south my music would be safe but with the Mac not sure if this is recommended
  22. macrumors 6502

    Oct 11, 2012
    How big is your "huge" collection, and what fraction of it do you use often?

    If the active part doesn't use up too much of your 128 GB SSD, just keep your library on the fusion drive and don't worry about managing it. The OS will migrate your least-used files to the HDD as needed. Your favorite iTunes stuff (likely a small part of the total) will benefit from the fast SSD speed.

    NO MATTER WHAT, you need to back up all of your stuff. Unless you have time to research other tools and configure and USE them, just use Time Machine. It's built in, easy, automatic, and reliable enough. Time Machine is MUCH more reliable than the common backup method (which is no backup at all).

    Just get a reasonably-priced external disk and dedicate it to Time Machine. Anything that's at least twice the size of the data you expect to back up is fine. If you think you'll fill 500 GB of your iMac disk, try to get a 1 TB or larger Time Machine disk. The more extra space you have, the more old stuff Time Machine can keep. If you accidentally delete or damage a file and don't realize it for a month or two, it's very nice if Time Machine still has an old copy. Speed isn't a big deal, except in the unlikely case where you need to restore the whole thing. I prefer a quiet backup disk; I want it connected and powered on all the time, and it normally runs about once an hour.

    For most people, adding extra partitions just makes more stuff to maintain, back up, and keep track of.
  23. macrumors 601

    Jun 29, 2010
    I got the 1TB Fusion drive and have about 350-400GB of music in total. I use iTunes quite a bit but don't listen to it all just a fraction at a time obviously. I think I'll just let Fusion handle it then. I manage my own library so I don't have my music in the "iTunes Music" folder on my PC. I want it separate from the default location in the iMac as well....as I tag & rename all my stuff and list my folders by artist/album/year. It was recommended to me to place my music in say Home/Music/Bob's Music/Jazz whatever genre etc does this sound right?

    As far as backups I will definitely do that have a 2TB external that I already do random backups on so I'm good there

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