Designate external drive as internal?

Discussion in 'macOS' started by ttturbine, Feb 26, 2016.

  1. ttturbine macrumors newbie

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    Feb 26, 2016
    #1
    So OSX designates drives as being internal or external, presumably based on which bus they are connected to. I wonder if there is any way to override this, and set a drive that is connected to an external port to show up as internal for management purposes?
    Thanks!
     
  2. simon lefisch macrumors 6502a

    simon lefisch

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    #2
    What would be the purpose of managing an external drive as an internal one?
     
  3. DeltaMac macrumors 604

    DeltaMac

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    #3
    You sound like a Windows user :D
    OS X really doesn't care if a drive is internal or external - only what type of bus connection is used, and the format of the drive and the various volumes - and does all of this without any help from you.
    You DO manage the drive and partitions yourself by naming them in some way so that you can determine which is which.
    There has never been drive letter assignments on OS X, unlike Windows in the past.
     
  4. simon lefisch macrumors 6502a

    simon lefisch

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    #4
    Actually I've been using OS X for the last few years and recently have been learning to use Terminal a bit more for searching/copying/partitioning/etc files/drives. I was genuinely curious if there was any particular benefit to managing an external drive as an internal.
     
  5. ttturbine thread starter macrumors newbie

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    #5
    Good question - I was wondering myself why the OS has an opinion on whether a drive is internal or external. The reason I want to do it is that I have a cloud backup subscription that allows me to backup internal drives, but not external ones. I have a mini with an 'external' drive that sits underneath it that is my boot drive, and a dead 'internal' drive. I want the computer to label the only permanently connected boot drive 'internal' for this reason.
    --- Post Merged, Feb 28, 2016 ---
    As I mention above, the reason I care is that the OS does label the drives, and it does matter for some applications. I am looking for what flags etc it is that the os uses, or whether it is simply which bus the drive is connected to.
     
  6. simon lefisch macrumors 6502a

    simon lefisch

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    #6
    Gotcha. I thought you had another purpose in mind. Are you not able to replace the internal drive in your mini? All you'd have to do is buy a new drive and clone your external to your internal (Carbon Copy Cloner will copy everything, including the recovery partition).
     
  7. ttturbine thread starter macrumors newbie

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    #7
    I suppose I could, but I have not, and don't really want to. What I'm wondering is how the OS labels the drives, and whether it can be changed, especially since I'm about to add more storage to it.
     
  8. DeltaMac macrumors 604

    DeltaMac

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    #8
    Ah, a dead drive in a mini.
    Not a difficult task to replace a non-working internal drive on a mini - although those that have two drive slots are much simpler with the slot that is closer to the bottom cover, which is the slot most often used for single drives.

    My take on what the system uses - is that it identifies the actual hardware connection. For example, the hardware knows if the hard drive is in the upper or lower slot on those minis with both slots. The internal bus will "usually" be faster, and thus give better performance, assuming everything else is equal. On a mini, using a USB 3 external drive may be near in speed to a Thunderbolt external drive, though I think you lose the advantage with thunderbolt because of the extra expense involved with the TB externals.
    And, external storage on a mini has a lot of options. A local drive can have the same styling as a mini, giving you a significant amount of additional external storage, with a box having the esthetics of the mini (if you appreciate that :D )
    If the performance with an external is similar, or even better than the internal device, then where is the need to know what the system does with 'labeling' that device - other than using (and enjoying!) the results.
     
  9. ttturbine thread starter macrumors newbie

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    #9
    Thanks for the suggestions - what I really want to do is understand how the OS labels the drives as internal or external, and edit that. I imagine the, similar to the way the machine declares whether it 'should' have a DVD drive internally and the OS will or will not launch DVD player respectively, there is a way that the hardware is declared as having certain busses that are internal and external.
    As you point out, presumably there is some way the mini hardware declares it has two internal drive slots, and which they are, and that that is changed for each hardware variant.
    Speed isn't an issue for me. I'm not so much solving a practical problem as trying to understand how this works. Thanks!
     
  10. Fishrrman macrumors G3

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    #10
    OP:

    Quite frankly, the internal drive IS "internal".
    Any external drives WILL REMAIN "external".

    You are not going to change this.
    Insofar as the Mac OS is concerned, the drives "are where they are", and that's that.

    All you have to do is rename the external boot drive to whatever name you wish.
    Put its icon in the upper-right-hand corner of the display, that's the normal position for the boot drive icon.

    Questions:
    When you open Disk Utility, do you "see" the internal drive?
    If so, can you re-initialize it ("erase" it)?
     
  11. ttturbine thread starter macrumors newbie

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    #11
    Well, it's not quite that simple - certainly with the case of DVD drives there are patches that change whether the machine 'expects' a DVD drive, and I know that this is something that the hackintosh community deals with a lot because clearly their builds need to specify this (although their solutions won't help me, since mine is legit). It clearly can be changed, because people do it, I just need to figure out how to do it on legit builds.
    On the renaming issue - thanks - I'm on top of that.
    --- Post Merged, Feb 29, 2016 ---
    I found this:
    http://apple.stackexchange.com/questions/108100/make-scsi-appear-as-internal-hard-drive
    But it appears to be out of date, and I don't have those ktexts - it looks like this does reside in ktexts though, so should be just a case of tracking it down.
     
  12. DeltaMac macrumors 604

    DeltaMac

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    #12
    Yeah, I think the patch for the DVD Player app is just that, so it doesn't expect an internal drive on a Mac that doesn't have one. And, not needed if the Mac did not have an optical drive installed originally.
    So, not really analagous to storage devices, as the use of the DVD software is just not the same as how the hardware decides where storage is attached.
    Hackintosh needs to let the OS X system know how to determine drive presence. There's no real need to do that on Mac hardware, as the firmware and OS X know how to talk to each other. Not so simple on hackintosh due to the variety of different hardware/mother boards, etc, that may be encountered.
     
  13. ttturbine thread starter macrumors newbie

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    #13
    I don't know how the DVD drive patch works, but my understanding is that it simply toggles whether the attached DVD drive is declared as 'internal' or 'external'. By default OS X won't launch DVD player if the attached DVD player is not flagged as 'internal' - it's flipping this flag that allows it to launch.
    I'm pretty sure this is declared with ktexts, not firmware, since that's how it's fixed on the hacks, but again, I'm not certain. The issue with the Htoshs is not the variety of boards, but the fact that the buses are not declared as 'internal' in OS X. Again, it's simply declaring them in a ktext to be internal.
     
  14. DeltaMac macrumors 604

    DeltaMac

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    #14
    You did notice that optical drives work for read/write access, without any distinction of internal or external connection. The issue is ONLY with Apple's DVD Player for viewing DVD movies. Other kinds of data functions work without difficulty, assuming the drive is actually compatible with the Mac.
    Most are.
    My point is that the DVD Player app has no affect on other types of storage, and internal or external storage devices work with most anything. The DVD Player app prohibition is not a system issue, otherwise you would not be able to use other software, such as VLC to view DVD movies.
    One exception, of course, is setting up a Boot Camp partition, which won't work on external drives.
    I don't know if Boot Camp is important to you, but then Windows has been quite challenging to boot from an external until quite recently. I expect that would be why that would be disallowed on an external drive partition
     
  15. ttturbine, Feb 29, 2016
    Last edited: Feb 29, 2016

    ttturbine thread starter macrumors newbie

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    #15
    link
    Sure - I'm just expressing my suspicion that the same underlying system of declaring a drive as internal or external is at work in both cases. VLC certainly ignores the flag, which is one approach, but some software doesn't, hence the patch to declare a dvd drive as internal.
    Boot Camp isn't important to me, but what I am trying to do is instruct the computer to treat a particular drive as internal or external for the purposes of managing it. With Thunderbolt or eSATA connections there is no real speed issue, and I want to be able to declare a drive as internal for OS management purposes.
    ----
    Digging into this a little more it seems that this is to do with whether the drive is declared as 'ejectable' by the controller. It seems that the housekeeping is done differently to allow 'external' drives to be ejected more quickly.
     
  16. DeltaMac macrumors 604

    DeltaMac

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    #16
    Now I am confused.
    How does it help YOU if you have an _external_ device that you have decided will be identified as _internal_ ? (or something else?)

    Other than thinking that you should be able to do that, Can you think of some scenario where that distinction might be useful to you?
    Hate showing my perverse streak here, but I just don't understand...
     
  17. ttturbine thread starter macrumors newbie

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    #17
    Digging into this a little more it seems that this is to do with whether the drive is declared as 'ejectable' by the controller. It seems that the housekeeping is done differently to allow 'external' drives to be ejected more quickly.
    As I mentioned, I have a backup service that will only back up 'internal drives'. That was my initial motivation in figuring this out.
    Thanks for your help - I do understand that it can be frustrating when it looks to you that someone is asking the 'wrong question', but my interest is in learning more about how the filesystem works and being able to set this flag arbitrarily. I'm not interested in being talked out of being interested in this ;)
     
  18. DeltaMac macrumors 604

    DeltaMac

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    #18
    I (kinda) get it.
    But then an external drive is naturally simple to backup locally, and a local backup copy to a second external could be a good addition to your backup plan.

    You say your internal drive is dead. If you replace the internal drive, then that would be another solution to your issue, eh?
    (just sayin'... :D )
     
  19. ttturbine thread starter macrumors newbie

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    #19
    Thanks - yes - the most direct solution to the immediate problem would be to pop open the case and swap the drives.
    Given that I'm not going to do that, my issue is that the (cloud) backup software will only use an 'internal' drive as its source. I have no 'internal' drive to use, so want to figure out how to set the drive I use to be 'internal'.
    I've been looking into rEFInd, which looks like it is able to edit EFI settings prior to boot, which may be what I need. I appreciate your help!
     
  20. simon lefisch macrumors 6502a

    simon lefisch

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    #20
    Internal drives are pretty cheap nowadays. In my eyes, that would be the best/easiest solution to your problem. Trying to go thru and change the way OS X flags the drive as internal/external seems more work than it's really worth. It's also very easy to swap out (I did it to my friends mini not that long ago), but to each his own
     
  21. ttturbine thread starter macrumors newbie

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    #21
    #19
    Thanks - yes - the most direct solution to the immediate problem would be to pop open the case and swap the drives.

    One thing that I have discovered, which doesn't really answer my question, but is interesting, is that files that reside on external drives can be treated as if they are on internal ones by using symlinks. That is to say that hard-linking a folder on the internal drive to the external drive makes OS X treat the folders as being logically on the internal drive...
     
  22. Fishrrman macrumors G3

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    #22
    OP wrote above:
    "As I mentioned, I have a backup service that will only back up 'internal drives'. That was my initial motivation in figuring this out"

    I think you're going to have to find another backup service.
    (That's intended to be a serious answer.)

    What kind of "backup service" denies you the opportunity to "point" the service towards the particular drive you're attempting to "back up" ???

    Question:
    How much data (in gb) do you have to backup?
     
  23. ttturbine thread starter macrumors newbie

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    #23
    Thank you - let's just take this specific situation that sparked my question out of the mix. I can solve it, and I promise I will just switch the drives out. Done.

    Now, what I want to know is how to change the way OS X designates drives as being internal or external. I've seen how it's done on hacks using ktexts, and suspect that it is an issue with the specific drivers on the bus declaring anything attached to them, but I'm using a vanilla system. Thanks!
     
  24. Fishrrman, Mar 2, 2016
    Last edited: Mar 2, 2016

    Fishrrman macrumors G3

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    #24
    OP wrote:
    "Now, what I want to know is how to change the way OS X designates drives as being internal or external."

    I don't believe the Mac OS really distinguishes or "cares" (as much as an OS can care) about -where- the drive it's running from is located.

    Rather, the Mac looks for bootable versions of the OS, and then boots from whatever volume it finds that is:
    a. bootable
    and
    b. is selected by the user to be the boot drive.
    Things have been this way on the Mac for a long, LONG time.

    When you open Disk Utility, it will show you WHERE the drives are.
    But it won't let you re-designate a drive to be "internal" or "external" because (again) the drive's physical location isn't really that important in the overall scheme of things.

    I'll reckon that this is why one can even concoct a "fusion drive" from an internal AND an external drive if one so desires. The Mac and the Mac OS aren't particular about such things.

    Again -- short of physically opening the Mac and moving the external drive -inside-, I doubt there's "a software solution" that can do this.
    I will -guess- that it -is- doable in Windows, but I know nothing about Windows (Mac guy since 1987).

    Something that just occurred to me:
    If you have an external drive that you want to be "recognized" as internal, I wonder if the following might be the workaround:
    - create a "fusion" drive comprised of the existing internal drive AND the external drive.
    - the two drives will now be "fused as one volume" (combining the storage space of both drives)
    - if you are using some kind of automated backup system that backs up the "drive inside", it will now backup the "fused" drive.
    Proviso:
    - you can't disconnect the external drive while the computer is running, as the disk directory is "spread across" BOTH drives, and you could lose all the data.
    - VERY IMPORTANT! You MUST back up BOTH drives first, because creating a fused drive will wipe out any existing data on the drives. Then, restore from either drive to the single fused volume.

    It's certainly possible to create a fusion drive between external + internal (although I've never tried it).
    Whether this will work for you -- you'll have to try it and get back to us ...
     
  25. ttturbine thread starter macrumors newbie

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    #25
    I'm pretty sure it does. The flags 'removable' and 'detachable' tell the drivers (and possibly the OS) things about how aggressively they can cache in light of whether the drive is likely to be 'hot swapped'.

    That's certainly true, but I'm not talking about selecting a boot drive, it's easy to boot from an 'external' drive.

    I see it the opposite way - it is important to the OS to know which drives are hot swappable, and the physical location is shorthand for that information. My sense is that the OS doesn't want people messing with it because designation a hot swappable drive as 'internal' could have a greater likelihood of creating errors on ejection.

    There's certainly a software way to do it - it's done all the time on Hackintoshes using ktexts to patch the 3rd party SATA drivers they are using. Now my suspicion is that nobody has been motivated enough to reverse engineer the Apple SATA drivers to do this.

    That's a really interesting approach - I'll have to try it - thanks!
     

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