A question for fusion drive users

Discussion in 'iMac' started by AppleHater, Oct 14, 2015.

  1. AppleHater macrumors 6502a

    Joined:
    Jun 9, 2010
    #1
    if you have used fusion drive for a while where the drive is filled up more than half, I'd like to ask you how is the performance nowadays compared to the early days

    I expect it to slow down as you fill up the drive and the fragmentation happens. I want to know if it gets as bad as hard drive or actually being a fusion drive has done a good job of keeping things optimal still.
     
  2. whodatrr macrumors 6502a

    whodatrr

    Joined:
    Jan 12, 2004
    #2
    Mine has hovered around 50% for a while, and I haven't noticed a difference. Most of what you interact with is in the SSD anyhow.

    Perhaps there's occasionally a bit mor shuffling in the background, as things get shifted about? But this doesn't impact performance, it just piques curiosity... Wondering what's being shifted, and why?
     
  3. AppleHater thread starter macrumors 6502a

    Joined:
    Jun 9, 2010
    #3
    The shuffling doesn't happen, hopefully not while you're using, right?
     
  4. cbrand493 macrumors 6502

    Joined:
    May 19, 2015
    Location:
    Perth, Australia
    #4
    Don't think you understand how the fusion drive and OSX works.

    The OS moves most regularly used files/apps to the SSD automatically. An SSD is an SSD so it won't slow down unless it's >90% full which I don't believe OSX allows. The HDD part holds everything else. Files are only moved between the two if they become more frequently used than whats on the SSD. So providing you use your iMac for pretty much the same stuff all the time, eventually nothing will need to be moved.

    As for fragmentation, that's primarily a NTFS issue. HFS+ filesystem controls the fragmentation/defrag of files automatically.
     
  5. AppleHater thread starter macrumors 6502a

    Joined:
    Jun 9, 2010
    #5
    I do understand and that's why I'm asking to find out the effects of the amount of frequently used contents being much larger than the SSD portion of the size.
     
  6. cbrand493 macrumors 6502

    Joined:
    May 19, 2015
    Location:
    Perth, Australia
    #6
    OSX will be stored on the SSD then the rest will be ranked in order of frequency of access and moved to the SSD until it's almost full. If something on the HDD moves above something on the SSD, I think files are only copied between the two when the iMac is idle so it doesn't interrupt your work.
     
  7. JustMartin macrumors 6502a

    Joined:
    Feb 28, 2012
    Location:
    UK
    #7
    From the research on anandtech, Fusion provides block level caching with 4Gb reserved for new content - so your initial file loads will be going to the SSD. Promotion/demotion of content takes place when the machine is idle. I suspect (but haven't researched) that quite a lot of the non-core OS is on the hard disk because I rarely reboot and don't often use the underlying OS stuff.

    My late 2012 is about 50% full and I haven't noticed any degradation in speed over that time.
     
  8. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #8
    I have tested this with tools from www.digitalloydtools.com: http://diglloydtools.com/disktester.html

    The FD only behaves partially like a regular HDD as it fills up. As it fills up there is an initial dropoff in speed, then it remains very flat out to over 95% full. It does not have the extreme slowdown of an HDD as it gets really full.

    My recommendation is get SSD if you can but there is definitely a good usage case for FD. It is *way* better than a HDD, and the 3TB model gives a lot more space than is available or affordable on SSD. Someone who spends their budget on an SSD iMac than must resort to a cheap, slow bus-powered portable USB hard drive for frequently-used files is probably getting less overall performance than if they'd just gotten FD.
     
  9. AppleHater thread starter macrumors 6502a

    Joined:
    Jun 9, 2010
    #9
    How much is the initial drop off is the very part that I'm curious to learn. 10%? 30%?
     
  10. kappaz macrumors member

    Joined:
    Feb 28, 2008
    #10
    I have the late 2012 iMac and the performance is as good as ever. However, DriveDX, Disk Drill, and other disk tools show that wear level of the SSD at 67%, so only 33% remaining. While the regular 1tb drive is healthy at 89% remaining. I was worried about this and took it into an Apple store, but of course it passed all their diagnostics. The cost to get the SSD replaced was over $400..for 128gb, thanks but no thanks. The genius there didn't seem to think it was an issue. I don't do anything crazy to really wear it out. I know they said for the new model they adjusted the algorithm to not be as aggressive in moving files to the ssd. For the price discrepancy between the fusion drive and ssd, I think it's worth getting the fusion drive.
     
  11. cbrand493 macrumors 6502

    Joined:
    May 19, 2015
    Location:
    Perth, Australia
    #11
    Wow an SSD being almost dead at only 3 years old?! Apple SSDs must be bloody awful. Standard SSD lifespan is usually 10+ years!
     
  12. AppleHater thread starter macrumors 6502a

    Joined:
    Jun 9, 2010
    #12
    If that's the case the 128GB SSD port of the fusion drive will likely overwork and wear quicker, right?
     

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