Mac Finder meta data location

(Tony Voss) #1

I posted this on SlackBITS and Adam suggested I post it here too.

I have been backing up one removal volume to another (not boot volumes) using SuperDuper!, which I find excellent.

However, the changes to my source volume were largely insertions of comments on the files, which I added into the Comments field using the file’s Info window and then displayed using the Finder View option. These comments did not get copied across by SuperDuper! Neither did settings of the Finder View options, such as which metadata to display and icon size, the open/close status of folders in hierarchical lists, etc.

Dave Nanian of ShirtPocket/SuperDuper! says metadata on the drive is copied across, but the metadata may not be on the source volume - presumably it is on the boot volume. I noted I was using the Smart Update option, but he did not see that as relevant. He says all data is copied, including any metadata.

Does any kind soul know about this or can they point me to a knowledge base article? I am wondering if there is any way of forcing the metadata onto the relevant volume?

PS My boot drive is APFS but the removable volumes are HFS+.

(Curtis Wilcox) #2

Comments added to a file or folder through the Get Info panel are a kind of extended attribute. Based on the Wikipedia extended file attributes article and Show me your metadata: extended attributes in macOS Sierra, I believe extended attributes are not stored as part of the file but as part of the volume’s catalog (I’m sure the details are different in HFS+ and APFS but the concept the same). The comments on files on your source volume are also stored on your source volume, not your boot volume; if you connect the source volume to a different Mac, the comments will still be there.

Maybe SuperDuper! doesn’t copy all extended attributes, only some. Or maybe it doesn’t copy extended attributes when the file itself hasn’t changed; adding a comment or tags to a file doesn’t change its last modified time but others like adding a custom icon does. In Terminal, using the touch command to change a file’s last modified time may be sufficient to make SuperDuper! recognize it needs to be copied.