matlinp
Level 1 (4 points)
Desktops

Q: Possible hardware problem?

This is a followup to a previous post I had made a few weeks ago. 

 

Background - I have a mid-2010 iMac (11,3) with 12 GB RAM and a 1 TB disk.  Late last year, I noticed a significant slowdown in applications starting and more often than not, the system would hang when rebooting, requiring a hard reset in order to reboot.  After playing with things off and on, I did a fresh install of OS X on an external drive and that appeared to work fine until I turned on Time Machine.  Again, playing with things over a period of time led me to try taking everything off line except keyboard, mouse, external boot drive and Time Machine drive.  As long as Time Machine was turned off, all was well; turning TM on, caused the system to get real slow or hang when doing things like bringing up the disk utility, file manager, etc.  Finally, did a fresh install of OS X on a new external drive, again only keyboard, mouse, external boot drive and TM drive.  No updates, no added applications.  Same result.  As a double check, I took my original external boot drive to a 2008 iMac (8,1) and booted off of it and attached a blank disk for use as a TM drive.  No problems with backups.

 

Obviously, there is (or at least appears to be) a hardware problem that prevents TM from operating properly.  As I said, this is a six year old iMac and I'm ready to throw in the towel on it and replace it, but I still would be interested in any ideas that anyone has as to what might be going on here.  I should add that along the way, I've done (many, many times) the usual routine for resetting Time Machine - deleting the TM plist file and re formatting the TM drive.

 

Has anyone come across anything anywhere similar to this?

 

Thanks.

iMac, OS X El Capitan (10.11.3), Time Machine via USB hub

Posted on May 14, 2016 7:16 PM

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matlinp

Q: Possible hardware problem?

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  • by matlinp,

    matlinp matlinp May 23, 2016 11:55 AM in response to notcloudy
    Level 1 (4 points)
    Desktops
    May 23, 2016 11:55 AM in response to notcloudy

    nocloudy, I think you're relating a much more complicated situation than is really the case.  Assuming that OS X follows the pattern of other Unix-based OS', when you boot off of an external drive, the internal drive, boot or otherwise, is really not in the picture except as yet another external drive (in this case, external to the boot environment).  The advantage that an internal drive has, of course, is that it uses the Mac's internal bus, which is faster than USB, hence etresoft's comments about slow boot times, etc.  And if what you are supposing were the case, it wouldn't explain why, when this same external boot drive that is having problems with Time Machine backups is used as the boot drive for another iMac, everything works fine.

     

    Appreciate the input though.

  • by etresoft,

    etresoft etresoft May 23, 2016 8:13 PM in response to matlinp
    Level 7 (29,198 points)
    Mac OS X
    May 23, 2016 8:13 PM in response to matlinp

    Hello again matlinp,

    The number of files, or lack thereof, has no bearing on the speed of a hard drive. The only time free space becomes and issue is when you run very low on free space on your boot drive. On portable machines, the OS will start to do extra work to keep from running out of space. Because once a Mac runs out of hard drive space, it is essentially game over. From the reports I have seen, it is not possible to recover from running out of disk space.

     

    You have talked about a number of different configurations and it is difficult to keep all that straight. If I understand correctly, your machine was slow to start apps and didn't want to shutdown. When you re-configured that machine to test from an external boot drive, Time Machine did not work properly. When you make a number of simultaneous changes, it can be difficult to identify just what is going wrong. The bottom line is that USB 2.0 simply is not very fast and El Capitan is not very stable. If it is working good for you, then don't mess with it. If it isn't, then reformat the hard drive and reinstall from scratch. You have gone through so many different configuration that you really couldn't identify any particular problem at this point anyway. I suggest you reinstall the OS onto your boot drive and see how it runs.

  • by notcloudy,

    notcloudy notcloudy May 24, 2016 7:23 AM in response to matlinp
    Level 4 (1,190 points)
    Desktops
    May 24, 2016 7:23 AM in response to matlinp

    matlinp wrote:

     

    nocloudy, I think you're relating a much more complicated situation than is really the case.  Assuming that OS X follows the pattern of other Unix-based OS', when you boot off of an external drive, the internal drive, boot or otherwise, is really not in the picture except as yet another external drive (in this case, external to the boot environment).  The advantage that an internal drive has, of course, is that it uses the Mac's internal bus, which is faster than USB, hence etresoft's comments about slow boot times, etc.  And if what you are supposing were the case, it wouldn't explain why, when this same external boot drive that is having problems with Time Machine backups is used as the boot drive for another iMac, everything works fine.

     

    Appreciate the input though.

    Just a thought - disk to disk transfer is always slow - slower still when jumping through hoops.

     

    - personally - i would move files I do not use a lot from the internal drive to an external drive - freeing up space on the internal drive - and going back to that as a boot drive - as the mac that does not have a problem may simply have more empty space on the internal drive.

  • by matlinp,

    matlinp matlinp May 24, 2016 5:25 PM in response to etresoft
    Level 1 (4 points)
    Desktops
    May 24, 2016 5:25 PM in response to etresoft

    etresoft, undoubtedly I was not as clear as I could have been about the sequence of events and the various configurations.  However, the bottom line is that, in the end, I ended up with only four devices attached (all USB): keyboard, mouse, one 1 TB external drive used as a boot drive, and one 5 TB drive used for Time Machine.  In fact, there were two separate combinations of the USB drives.  Each time, even with a fresh installation of El Capitan with no updates and any other applications installed, Time Machine ended up hanging and eventually hanging the system.  These same boot drives, when attached to an older iMac and used as the boot drive, did just fine with a 5 TB USB drive (one of the previously used TM drives that had helped hang the system).  While I imagine that the ultimate elimination test would be to take this older iMac and use it in place of my mid-2010 iMac, I think the problem is pretty obvious - hardware within the iMac.

     

    I've been dealing with computers of all sorts since 1978 - development, IT, support, etc. - so, I feel as if I'm on fairly solid ground with my conclusion.  Even so, the engineer in me is just really curious, even after all this time spent trying things, as to what is going on.  I'll be getting a new iMac sometime in the near future, but I'm still curious.

     

    All the same, I am extremely grateful for all the help and suggestions I've received here.

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