Creating bootable USB on a Mac

[djdawson]

I just wanted to share my experience of successfully creating a bootable Spinrite 6.1 USB stick on my Mac (the last of the Intel 16" MacBook Pro laptops running the latest Sonoma 14.4.1 macOS). There's really nothing special about the process if you've ever done a similar thing to create a bootable device, such as a "pfSense" boot image, since it's the same process described in many places on the web using the "dd" command in the Terminal app. I used the process as described in this Centos support page, but it's also shown in this short YouTube video (though I used the "/dev/rdisk2" device instead of the "/dev/disk2" device shown in the video for the "of=" parameter, since "r" devices are a bit faster, but for this small Spinrite image that shouldn't really matter). I happened to use an old 8 GByte Sandisk USB3 stick I had sitting around, but I don't think that's important. The "sr61.img" file in the "sr61.zip" download file worked perfectly, and is currently running on my wife's very old Asus laptop. Here's the exact command I used after unmounting the USB drive (which was /dev/disk2 on my system but you should be extremely careful to verify that you're specifying the correct device for your USB stick):

sudo dd if=sr61.img of=/dev/rdisk2 bs=1m status=progress

 

[Steve]

@djdawson : Thanks for sharing the approach you took. I agree that using the built-in native “dd” command is THE best/right way for a power user to tackle moving an .IMG file to a USB device. And I also agree with your admonishment:

but you should be extremely careful to verify that you're specifying the correct device for your USB stick

For that reason, another Mac user pointed to a VERY slick, minimal and fool proof solution. It's some open source freeware called balenaEtcher at: https://etcher.balena.io/#download-etcher. It's large (452MB installed) for what it does, but it can be uninstalled after it does its job. And its HUGE benefit is that it's just impossible to get wrong. Thanks again for sharing your “correct” way of doing this!

 

[Tazz]

t's some open source freeware called balenaEtcher at: https://etcher.balena.io/#download-etcher. It's large (452MB installed) for what it does, but it can be uninstalled after it does its job.

There is a portable "version"
https://portableapps.com/apps/utilities/balenaetcher-portable

Maybe have a look at the 'How to' page first.
https://portableapps.com/support

 

[Steve]

There is a portable "version"
https://portableapps.com/apps/utilities/balenaetcher-portable

Yeah... I saw that, @Tazz, but I thought the portable version was only for Windows?

 

[Tazz]

Yeah... I saw that, @Tazz, but I thought the portable version was only for Windows?

Ahhh yes.
Sorry about that, I overlooked the context of the thread.
Was focusing on the "Unread" and "New" tags.

 

[Not despondant]

I just wanted to share my experience of successfully creating a bootable Spinrite 6.1 USB stick on my Mac (the last of the Intel 16" MacBook Pro laptops running the latest Sonoma 14.4.1 macOS). There's really nothing special about the process if you've ever done a similar thing to create a bootable device, such as a "pfSense" boot image, since it's the same process described in many places on the web using the "dd" command in the Terminal app. I used the process as described in this Centos support page, but it's also shown in this short YouTube video (though I used the "/dev/rdisk2" device instead of the "/dev/disk2" device shown in the video for the "of=" parameter, since "r" devices are a bit faster, but for this small Spinrite image that shouldn't really matter). I happened to use an old 8 GByte Sandisk USB3 stick I had sitting around, but I don't think that's important. The "sr61.img" file in the "sr61.zip" download file worked perfectly, and is currently running on my wife's very old Asus laptop. Here's the exact command I used after unmounting the USB drive (which was /dev/disk2 on my system but you should be extremely careful to verify that you're specifying the correct device for your USB stick):

sudo dd if=sr61.img of=/dev/rdisk2 bs=1m status=progress

Hey ddawson,
I tried following your process, but I must be missing something, here is my terminal output, can you see what I'm doing wrong?

jim@Jim-MBP-M3 SpinRite6.1 % diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk0
   1:             Apple_APFS_ISC Container disk1         524.3 MB   disk0s1
   2:                 Apple_APFS Container disk3         4.0 TB     disk0s2
   3:        Apple_APFS_Recovery Container disk2         5.4 GB     disk0s3

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +4.0 TB     disk3
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            11.3 GB    disk3s1
   2:              APFS Snapshot com.apple.os.update-... 11.3 GB    disk3s1s1
   3:                APFS Volume Preboot                 7.2 GB     disk3s2
   4:                APFS Volume Recovery                1.0 GB     disk3s3
   5:                APFS Volume Data                    1.9 TB     disk3s5
   6:                APFS Volume VM                      20.5 KB    disk3s6

/dev/disk4 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *4.1 GB     disk4
   1:                 DOS_FAT_32 SPINRITE61              4.1 GB     disk4s1

jim@Jim-MBP-M3 SpinRite6.1 % ls -laFG     
total 17080
drwxr-xr-x  6 jim  wheel      192 Aug  9 09:41 ./
drwxr-xr-x@ 6 jim  wheel      192 May 29 21:53 ../
-rw-r--r--@ 1 jim  wheel     6148 Aug  9 09:41 .DS_Store
-rw-rw-rw-@ 1 jim  staff  8335872 Aug  9 09:44 spinrite.img
-rw-r--r--@ 1 jim  staff      592 Nov  8  2024 spinrite.txt
-rw-r--r--@ 1 jim  staff   393176 Nov  8  2024 spinrite.zip
jim@Jim-MBP-M3 SpinRite6.1 % sudo dd if=./spinrite.img of=/dev/disk4 bs=1m status=progress
dd: /dev/disk4: Resource busy
jim@Jim-MBP-M3 SpinRite6.1 % sudo dd if=./spinrite.img of=/dev/disk4 bs=1m status=progress
dd: /dev/disk4: Resource busy
jim@Jim-MBP-M3 SpinRite6.1 %
jim@Jim-MBP-M3 SpinRite6.1 % sudo dd if=./spinrite.img of=/dev/disk4 bs=1m status=progress
Password:
dd: /dev/disk4: Resource busy
jim@Jim-MBP-M3 SpinRite6.1 %

 

[PHolder]

dd: /dev/disk4: Resource busy

Not a Mac user, but with a little help from a LLM, try:
diskutil unmountDisk /dev/disk4

 

[Not despondant]

Not a Mac user, but with a little help from a LLM, try:
diskutil unmountDisk /dev/disk4

Yep that did it. What was causing me a bit of hesitation was once I unmounted the disk, would it have the disk number once remounted. But I guess that's due to my own knowledge limits of how still connected but unmounted disks can be accessed.
Thanks again!

 

[AlanD]

Yep that did it. What was causing me a bit of hesitation was once I unmounted the disk, would it have the disk number once remounted. But I guess that's due to my own knowledge limits of how still connected but unmounted disks can be accessed.
Thanks again!

That would have been because SR was unable to get an exclusive lock on the drive whilst it was still mounted and available to MacOS. Once it is unmounted, SR can lock it.