I am trying to make a virtual machine using VirtualBox. I have been following the comment David Anderson made for me here on this post (his comment I am talking about is at the bottom): Install macOS Sierra on VirtualBox?

I have gotten to his step #3 and finished it. I am now at step 4, but I haven't started step 4.

Before I finished this process I thought it might be a good idea to make a time machine backup of my drive in case I do anything wrong, also I haven't made a backup in about 150 days.

I'm just wondering if making a Time Machine backup with a sparse disk image containing a bootable installer will be a problem for the Time machine backup?

These are my computer specs in case they are needed for reference:

Macbook Pro mid-2014, Running macOS High Sierra 10.13.6 (natively)

  • Whats the problem with "old fashion" just copy the files to a external drive?
    – Asher
    Commented Jul 18, 2020 at 16:53
  • I don't have an external drive or even a usb thumb drive that is empty and free of storage, so I was cautious of putting the bootable installer or making a new volume on one of those external drives. I don't know if that makes sense, but that's what I decided to go with. Plus, I find it easier to do everything from the drive I am currently running on.
    – Arlen
    Commented Jul 18, 2020 at 16:58
  • @Asher do you know the answer to my original question?
    – Arlen
    Commented Jul 18, 2020 at 18:04
  • I'm not that familiar with VirtualBox, this doesn't seem like a very safe way to do a backup. If your in an emergency situation and just need to "backup" things someplace on your computer you might try and borrow a computer from a friend?
    – Asher
    Commented Jul 18, 2020 at 18:10
  • I haven't actually used VirtualBox yet. I only made a sparse disk image that contains a bootable installer. That sparse disk image would then be used to create an ISO file, and once that ISO file is created it would be used in VirtualBox by transferring the ISO file to a virtual machine and then booting up the macOS ISO from there. But I haven't done any of that yet. I only made a sparse disk image and then made a bootable installer on that sparse disk image. The sparse disk image is sitting on my desktop, and it's on the drive I am running from.
    – Arlen
    Commented Jul 18, 2020 at 18:37

2 Answers 2


I would absolutely encourage you to stop and make a Time Machine backup. There’s no harm in trying to manually twiddle things, but wouldn’t it be better to make your first backup in 150 days to an actual drive that’s connected?

You won’t run into issues with installers being downloaded - those are just are large files that get saved one time and then don’t change in the next hour’s backup.

  • Ok thank you for very much for your answer.
    – Arlen
    Commented Jul 27, 2020 at 20:02
  • Can you possibly help me make a virtual machine using David Andersons method? Or do you know someone that could possibly help me?
    – Arlen
    Commented Jul 27, 2020 at 20:14
  • Not at all, unfortunately. I specialize in VMware and backups and Unix mostly. (And knowing how Apple documents some things)
    – bmike
    Commented Jul 27, 2020 at 20:48
  • Do you know someone that could possibly help me? I don't want to mess up David Anderson's method.
    – Arlen
    Commented Jul 27, 2020 at 20:53
  • Good point - no sense auditioning to be a help vampire - always having a second question as soon as one is attempted. I would say let your posts sit for 2 weeks, find others to answer to get reputation to try your first bounty. Or hire someone you like to help guide you if you have more money than time to wait or learn.
    – bmike
    Commented Jul 27, 2020 at 21:23

At best, Time Machine will preserve the "sparseness" of the "sparse disk image containing a bootable installer" (saving space). Otherwise, Time Machine will "fill out" the backup to the maximum size of the sparse file. Which Time Machine does may depend on whether the backup is local or remote (and possibly other factors). In either case, Time Machine should do its job and backup the file.

However, there are some restrictions on what Time Machine excludes which may affect your Time Machine backup (so YMMV):


For example, if you have excluded your home folder/desktop where the file is located, it will be excluded.


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