Little-known fact: Windows/NTFS supports two completely different ways of what's usually called extended attributes in Unix parlance. You've got the fairly well

Little-known fact: Windows/NTFS supports two completely different ways of what's usually called extended attributes in Unix parlance. You've got the fairly well known ADS (alternate data streams), which are essentially unlimited in size, and then the more obscure EAs (extended attributes), which are much more like xattrs; they're stored in the MFT itself (MFT entries ~ inodes) and are limited, in total, to 64k. From usermode you can only access EA via the native API (NtQueryEaFile, NtSetEaFile), which are actually undocumented and read/write all EAs in one go (which presumably is because EAs are stored in a single file attribute, hence the 64k limit as well). NTFS also has various special attributes of files, like object IDs (which is basically a volume-unique ID for a file, much like an inode number, just that you can actually assign it as an application, and applications can open files by their object ID via OpenFileById. This is how some kinds of links in Windows continue to work even if you move their target.).