While cleaning up the hard drive on my MacBookPro I've encountered a large (128 Gb) dmg file. It won't mount and I get a "no mountable file systems" warning message. I am wondering what on earth this file could possibly be. 2012 MBP running Catalina.
MacBook Pro 13″, macOS 10.13
Hey generousmedium,
A .dmg file is a container file typically housing an installer. Apple's SD slot reader, if your Mac has one doesn't need a dmg file as all the necessary software is built into macOS.
Do you recall creating a custom .dmg in the past? Create a disk image using Disk Utility on Mac - Apple Support
We can say this does not appear to be a part of the core macOS files. It's likely something that was created after the fact.
Cheers!
I wonder if this could be a backup of one of the OP’s memory cards thar was made using Disk Utility and the HFS (not HFS+) file system, under an older version of macOS that still had support for plain HFS.
Drag it to the Trash. It can't be used anyway.
Thanks for the response, folks. I'm going to retrieve the lost bytes. 128 gigs ain't chicken feed. As far as my having made it myself, and subsequently having forgotten about it, that's quite possible. I suppose it's the size of the darn thing that gives me pause! But it's not as if I haven't lost mountains of data over the years.
Thanks, again for chiming in!
what is "Apple Built In SDXC Reader.dmg"
