SSD Boot Drive: What am I doing wrong

Discussion in 'Mac mini' started by output555, Apr 2, 2013.

  1. output555 macrumors member

    Joined:
    Dec 17, 2006
    #1
    I just finished setting up a new Samsung 840 550GB SSD as the boot drive for my late-2012 Mac Mini (2.3Ghz i7 with 16GB RAM) and seem to be getting sub-par speed results.

    The Samsung 840 500GB is capable of reaching 540 MB/s / 330 MB/s write/read speeds, whereas my configuration is hitting only a fraction of that at around 145 MB/s / 150MB/s speeds (yes, it's writing faster than its reading). So obviously my set-up is wrong.

    Here's how I've configured things:

    • Samsung 840 is the external boot drive connected through the Thunderbolt port (via Seagate Backup Plus Thunderbolt adapter). The OS and all apps are installed here. Configured Accounts to direct Home Directory/Users Folders to a second external USB 3.0 connected drive (see below)

    • Seagate Backup Plus 2TB HD, connected via USB 3.0 port, is where my User Home/Users folders reside with all data (Pictures, Music, Downloads, Documents, etc.) being stored here.

    • Internal 1TB HD is currently not used for anything.

    I researched this set up extensively and this is what was most recommended for optimizing performance. Obviously, that's not happening. The one thing that appears wrong to me is on my boot drive where original User accounts still reside I seem to also have some folders that may or may not belong there. Specifically, theses folders are:

    - data
    - Library (containing: Application Support, Autosave information, Caches, Calendars, Color Sync, Keychains, LaunchAgents, Logs and Preferences)
    - Shared (containing random apps folders)

    Is it possible these duplicate folders are causing some issues or is my set up's sluggishness due to something else?
     
  2. benwiggy macrumors 68020

    Joined:
    Jun 15, 2012
    #2
    Can you clarify the setup? You have a Seagate drive with the User accounts on it via USB3. You also have a Seagate Backup TB adaptor, plugged into the TB port, and the SSD is somehow connected to that.
    (From a quick google, isn't the point of the Seagate adaptor to house Seagate Backup drives? Any reason you're not doing that?)

    Your User account should have a Library folder, with "parallel" or duplicate folders to those found at the top level of the disk. There should not be one at the /Users folder level (i.e. above each user domain).
    /Users/Shared is normal.
    /Users/data is not default, but perhaps something is putting it there on your setup.

    You don't want to stick the SSD inside the Mini and make a Fusion drive with the internal 1TB?
     
  3. output555 thread starter macrumors member

    Joined:
    Dec 17, 2006
    #3
    Technically, the Seagate Thunderbolt Adapter is to be used with with a Seagate drive but in fact you can use it with any SATA drive, like the Samsung SSD. It just plugs in and you're all set.

    Pardon my ignorance, but when you say "Your User account should have a Library folder, with "parallel" or duplicate folders to those found at the top level of the disk. There should not be one at the /Users folder level (i.e. above each user domain)." what do you mean by "top level of the disk?" Which disk: the boot SSD or the data-storing Seagate HD? Also, when you say there shouldn't be a Library folder at the Users folder level, do you mean on the data-storing Seagate HD? If so, do you recommend simply deleting the Library folder on the Seagate HD?

    I've elected to not replace the original installed HD with the Samsung SSD because this voids the warranty. I'd rather go with this set up, albeit slightly awkward, until my warranty expires.

    Thanks!
     
  4. benwiggy macrumors 68020

    Joined:
    Jun 15, 2012
    #4
    The real problem is that you've split your OS X installation across two drives, which causes complications.
    By "top level of the disk", I mean the root hierarchy of the system disk: "/Library".
    I also mean that on a normal installation of OS X, there is no Library folder in "/Users".

    You said "on my boot drive where original User accounts still reside I seem to also have some folders".
    Hopefully what I've said may help you in determining whether they should still be there.

    That's why I suggested keeping the 1TB drive, adding the SSD inside, and creating a Fusion drive!
     
  5. output555 thread starter macrumors member

    Joined:
    Dec 17, 2006
    #5
    Not sure I've actually "split" the OSX installation. I installed it completely on the SSD drive. The change is redirecting the Home Directory to the second HD which seems to work for everyone else (when done correctly). I checked my Users folder in the data-storing only HD and there is no "Library" so that doesn't seem to be an issue. The User Library folder remains on the boot SSD.

    Again, I don't want to void my warranty by tampering with the original configuration. I can create a "Fusion" drive using externals.
     
  6. benwiggy macrumors 68020

    Joined:
    Jun 15, 2012
    #6
    You could, though you might run into trouble if one of them didn't power up for any reason.
     
  7. blanka macrumors 68000

    Joined:
    Jul 30, 2012
    #7
    You are measuring the writing speed by copying files? That is just plain stupid. Then you have in and out data streams on the same bus.
    To have a good measurements, the destination when testing read, or the source when testing write should be RAM.
    Make a Ram drive of 4GB, and test between that drive and your SSD.

    Oh, and the write speed of the 840 won't reach 330MB's. Expect it to top around 200 write, 530 read.
     
  8. output555 thread starter macrumors member

    Joined:
    Dec 17, 2006
    #8
    Who said I was measuring speeds by copying files? I wasn't. Why would I want to test speeds using RAM? That's not relevant. This isn't a comparison of RAM vs. SSD. It's simply an attempt to measure SSD read/write speeds of the SSD boot drive using Blackmagic's app.
     

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