Checking error log?

Discussion in 'Mac Basics and Help' started by biohead, Nov 22, 2014.

  1. biohead macrumors 6502

    Joined:
    Jun 18, 2010
    Location:
    West Drayton, UK
    #1
    Ever since I've set up my own fusion drive, I've had random hang ups and beachballs. I've run a few tests on each disk and I've no reason to suspect its a disk issue.

    Instead, I'm suspecting it's a poor sata connection - either a bad connection or a dodgy cable.

    Rather than cracking my iMac open straight away, is there any way I can open up an error log and look for sata related errors to try and see if I'm in the right area?
     
  2. Weaselboy Moderator

    Weaselboy

    Staff Member

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    Jan 23, 2005
    Location:
    California
    #2
    You can open Console app and look there for error messages, but I would be surprised if it gave you anything that would show it was a cable vs a bad drive.

    You could try running the Apple Hardware Test.

    The only sure way to test for cables it to boot to an external with the same drive and see if the problem goes away.
     
  3. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #3
    If there is anything t see, I'd think it would be in /var/log/system.log
    You need to be logged into an admin account to read it.
     
  4. Weaselboy Moderator

    Weaselboy

    Staff Member

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    #4
    That is actually the log you see when in the main screen of the Console app I mentioned.
     
  5. biohead thread starter macrumors 6502

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    Jun 18, 2010
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    West Drayton, UK
    #5
    The error log threw up quite a few I/O errors on my fusion drive, but not really in any detail.

    I've broken down the fusion drive into the two separate drives now, and restored a TC backup to both drives (minus all the files to save time). I've not had much time to play, but the very first thing I've noticed is the slow read speeds of the SSD (about 8-12MB/s). I'm not quite sure if its a faulty drive, cable, trim issue or what yet. Pretty resigned to the fact I'll have to crack it back open again shortly, although at least its not as bad as the newer ones!
     
  6. Weaselboy Moderator

    Weaselboy

    Staff Member

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    Location:
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    #6
    Yikes. TRIM would not cause that at all. It might cause somewhat slower writes speeds over time, but even no TRIM ever would not kill read speeds like that.

    No sure way to diagnose cable vs. drive without just swapping the SSD out to an external enclosure to eliminate the cable unfortunately.
     
  7. biohead thread starter macrumors 6502

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    Jun 18, 2010
    Location:
    West Drayton, UK
    #7
    It's certainly a strange one - I've got a couple of thunderbolt enclosures, so hopefully I'll be able to use one of those without being limited by the bus speeds (Not that that's gonna be an issue if it's an SSD fault!).

    If anything I'd prefer it to be the SSD rather than the custom HDD with the built in temp sensor!
     
  8. biohead thread starter macrumors 6502

    Joined:
    Jun 18, 2010
    Location:
    West Drayton, UK
    #8
    So, I've tested in a thunderbolt enclosure in my Macbook, and I got the same speeds :(

    So, just out of interest I decided to enable TRIM (still on 10.9 for now), and then run fsck -fyy from single user mode to trim the drive... read/write speeds are now back at 140/350 MB/s (over a portable TB enclosure).

    So now I'm not quite sure what to make of it, nor my next move. I guess I'll try to work out if this SSD has GC (It's a Sandisk U100, 64GB - surely an "ideal" fusion candidate).
     

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