What I gathered from discussions on the Haiku mailing lists was that -- sometime in the far far future -- file metadata will stay but the indexes will move out of the filesystem into an external location. This makes sense, since it allows you to index complex filetypes such as PDFs and web pages without affecting file system performance. I once worked on an index_server for Haiku that worked somewhat like Spotlight's daemon. A new and much improved version of index_server is already in the Haiku repos, but it's disabled for now. This will form the basis for moving indexes out of the file system.
On losing metadata: every modern filesystem in use supports extended attributes, so this shouldn't be a problem when copying files between BFS and NTFS, EXT4, btrfs, HFS+ or ZFS. The only filesystem that will cause problems is FAT32, which most people still use with USB drives. I don't know how that will be handled in Haiku.
I don't quite follow: when you say an "external location" do you mean in file(s) in the file system but not in the file system's internal structure itself?
With regard to most file systems supporting extended attributes: that's true (though FAT32 not supporting them is a huge caveat, and I also wouldn't be at all shocked to see some issues during conversion across FSes... I don't have personal experience though), but email, HTTP downloads, peer-to-peer, etc don't tend to support them, essentially guaranteeing you'll lose them if you transfer them across the Internet.
Also, it's really nice to not have to worry about, say, an EA-unaware POSIX app losing metadata... how many old-style Mac resource forks were lost during a simple file rename before mv was made resource fork-aware!
> I don't quite follow: when you say an "external location" do you mean in file(s) in the file system but not in the file system's internal structure itself?
That's exactly what I mean. My version of index_server stored the index in a directory called "index" in the root of every volume it indexed. I'm not sure what the new one does.
Note that moving the index out of BFS was merely an idea that was bounced around the ML.
On losing metadata: every modern filesystem in use supports extended attributes, so this shouldn't be a problem when copying files between BFS and NTFS, EXT4, btrfs, HFS+ or ZFS. The only filesystem that will cause problems is FAT32, which most people still use with USB drives. I don't know how that will be handled in Haiku.