Hello, Anyone know of relevant documentation that captures the difference between vfsStruct.f_fsid and fstat.st_ino ? sys/stat.h declares: ino_t st_ino; /* [XSI] File serial number */ AND sys/statvfs.h declares: unsigned long f_fsid; /* Filesystem ID */ Based on some tests, it seems that the st_ino is the number/inode_number that the filesystem identifies the file-resource by ? I observed that this number gets a unique value when I copy a file even when the Finder/FS utilizes the Space-Saver feature of MacOS. This value is identical to the results returned by the command ls "-i" . When copying via Finder, I am seeing distinct st_ino values for source and destination files. f_fsid seems to be identifying the File differently though, perhaps taking into account what Data/attributes objects the file resource points to ? I observed that this number gets an identical value when I copy a file even when the Finder/FS utilizes the Space-Saver feature of MacOS. So, the value of f_fsid seems to be copied over to the destination file record. Also, I could not find a way to display f_fsid via the ls command. On a related note, Any documentation regarding MacOS Finder/FS's Space-Saver feature or how it is implemented ? Thanks, Vikram.S.Warraich