Negotiated link speed Fusion Drive

Discussion in 'iMac' started by itsamacthing, Jan 25, 2013.

  1. macrumors 6502

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    Sep 26, 2011
    #1
  2. macrumors 603

    philipma1957

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    Apr 13, 2010
    #2

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  3. thread starter macrumors 6502

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    #3
    Thank you
     
  4. philipma1957, Jan 25, 2013
    Last edited: Jan 25, 2013

    macrumors 603

    philipma1957

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    Apr 13, 2010
    #4
    if you look above you see one is 3GB and one is 6gb. if you look here you see i have a 1.5tb fusion.


    the 500gb samsung and the 1tb hitachi. so the speed varies. on the disk test I am reading beyond 400 mbs so it is reading from the ssd at sata III 6gb speed. my fusion is diy but even an iMac stock fusion will have that mix.


    As an aside Apple annoys me in that fusion is really good and then they use a small ssd 250gb ssds are the minimum that they should use not 128gb.
     

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  5. thread starter macrumors 6502

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    #5
    Ok, this is disturbing. If Apple is sticking a Sata 2 HDD I'm there, I'm gonna return mine and go all SSD. I didn't buy this new imac to go back in tech time.

    ----------

    Hope we can find someone with a stock 2012 imac
     
  6. macrumors 603

    philipma1957

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    Apr 13, 2010
    #6
    the problem is not that they use the hdd the key to a good fusion experience is

    ssd to hdd ratio. my diy in the mini is 500 to 1tb or 1 to 2. so slower speeds take a long time to show up.

    the iMac is 128gb to 1tb or 1 to 8 or worse 128gb to 3tb which is 1 to 24. my setup won't stress my ssd much. but the stock fusion in an iMac will push that small ssd with lots of rewrites . A real shame since the tech /software is a great idea.

    Apple just got stupid cheap (penny wise pound foolish) about it.
     
  7. macrumors 68040

    Giuly

    #7
    The problem is that any hard drive is so slow that the benefit of SATA-III is neglectable.
     
  8. macrumors 603

    philipma1957

    Joined:
    Apr 13, 2010
    #8
    did you see my scores for my fusion drive. they are right above.

    long reads are 442MB/s

    Long writes are 335MB/s

    4k iops

    are:

    114MB/s random read

    15MB/s random write

    Maybe I don't understand what you mean by neglectable do you mean negligible ?
     
  9. macrumors 68040

    Giuly

    #9
    Read this.

    And that's what happens with your SSD, which is than combined in software into a single drive with the hard drive.
     
  10. macrumors 603

    philipma1957

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    #10
  11. thread starter macrumors 6502

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    #11
    You mean, all of you who made home made fusion with a large SSD and HDD are really happy.

    A traditional HDD would have a hard time saturating a sata II let alone Sata III connector. Unless it was in a raid array. But I'm still back on the fence about fusion vs over priced 768GB flash :confused:
     
  12. macrumors 6502

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    #12
    It's upto the user.

    There is no argument here: it's horses for courses.

    Some (perhaps including experienced) users, who use their computers mainly to just store older data and probably don't use them to process vast data sums all the time, are likely better off with Fusion-type set-ups, as they do not need to worry about the nitty-gritty of whether their data is being stored on a fast SSD-type device or a slower HDD-type one. So the Fusion deals with this for them in the background and they never have to deal with the minutiae of it, and they still manage to achieve around 80% of the SSD's speed, which is still a great thing above HDD speeds.

    Another type of user, perhaps one who uses high-end apps that require vast data resources (uncompressed video editors comes to mind), may prefer to use a separate SSD and vast separate external storage data. So they can have their archives definitely stored on HDD's, while open projects are definitely stored on SSD for 100% speed, and they can define their own storage needs more definitively for themselves.

    Brewing your own Fusion is an excellent idea, and it's great that Apple allows this to be done to the user's own wanting. The only thing is that the GUI could be done more intuitively to make such choices more transparent to users.


    This is why the 2nd drive has Negotiated Link Speed set to 3Gb, as HDD's can't make use of 6Gb, so you really don't need to worry about it. If it was a second SSD, then it would show NLSpeed of 6Gb, AFAIUI.
     
  13. macrumors 68040

    Joined:
    Jul 11, 2009
    #13
    This is a bit of a zombie thread, but disks will show a 6Gb link if they support that link speed. The homebrew fusion drive in my 2012 mini shows both the SSD and HD at 6Gb.
     
  14. macrumors 6502a

    Joined:
    Mar 8, 2008
    #14
    are you sure that model is SATA-III? If it was actually a SATA-III 6Gbps model its negotiated link speed would be 6Gbps.


    When I installed an SSD and new HDD in 2012 Mac Mini it showed both as 6Gbps because they were both SATA-3 drives. Same when I upgraded the drive in my iMac from a SATA-II to SATA-III drive the negotiated link speed matched the new drive.
     
  15. macrumors 6502

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    #15

    Ah I may have this wrong! I bought a Mac Mini 2012 in Jan.2013, so I guess it's likely to be SATA II only and run at 5400rpm only (gee thanks stingy Apple! Like how much would a 7200/SIII one have cost them extra!), hence why the Negotiated Link Speed must be showing 3Gb only.

    Does this make much performance difference over the SATA III 6Gb HDD's (presumably 7200rpm, as well?)? Especially when they are used just for storage or as the other half in a SSD+HDD Fusion Drive set-up, anyway?

    (BTW, thanks to both of you for clarifying that!)
     
  16. macrumors 68040

    Joined:
    Jul 11, 2009
    #16
    RPM and link speed are not directly related. In any case, a 5400 or even 7200 rpm spinning disk won't come close to saturating even a 3Gb link. My 2012 Mini's 5400 RPM drive was 6Gb/sec for what it's worth, but actual throughput was around 115 MB/sec which is about 0.9Gb.
     
  17. macrumors 6502

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    Apr 6, 2011
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    London, UK
    #17
    Oh I see, from those figures it's an entirely moot issue then, it seems.

    Weird how your Mini came with a SATA III HDD, while mine is came with only a SATA II one!? But really, not exactly worth complaining about to Apple, as it's pretty irrelevant anyway, isn't it!


    My Mini is basically home server, with DAS storage for everything I own, connected to a HDTV for Plex home theatre, and DAS stored in a cupboard nearby using 3m Thunderbolt cable for absolute silence (all these 4+ drive Thunderbolt enclosures make a bit more of a din than one would like if it was in the same room, IMO).

    I currently actually use my Mini's internal 1TB HDD for Time Capsule backup of the 256 SSD, as I figured that a rough capacity ratio of 4:1 (1000TB:256GB, HDD:SSD) for these incremental backups would be enough for the boot drive backups.
    Although now I'm now considering splitting the drive into two partitions instead, and having the first 256GB partition for a clone of the SSD, with the other ~744GB for Time Machine's of the SSD —seems more logical to have two options for a backup— and can boot from the clone of course, while restore from the Time Machine backups.

    (incidentally, for all my data, in the end I went for 2x Promise R6's in RAID 5 level, each one swapped-out installed HDD's with all 4TB Hitachi Deskstar HDD's — one R6 Time Machine backed-up to the other R6, giving 24TB's backed-up to another 24TB's!
    Worth the hefty cost outlay as it's enough storage for next 3-4 years, is backed-up safely across two separate enclosures in case one fails entirely, and makes use of the fast Thunderbolt interface rather than anything else which would be much slower. So far, seems to be working a charm.)

    ...now if only I could also backup to the cloud! As even though I'm on a 100/10mbps line, even a couple of TB's would take MONTHS to get into the cloud. Bugger!
     
  18. macrumors 65816

    AppleNewton

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    #18
    what is the model of the 1TB hard drive? one check of that can determine why it is or isn't reporting 6Gbps.

    like stated earlier, there are 5400rpm and 7200rpm 6Gbps SATA-III drives. just depends on the model you have
     

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