Microsoft's published limits are 32,767 character with their extended "\\?\" prefix. Relative paths are always limited to to a total of MAX_PATH characters (260).  I believe this stems from local paths, so you have "D:\some 256-character path string " which could total up to 260. These are Microsoft's limitations and they seem to recommend not exceeding 259 (+1 for the NULL) characters for maximum compatibility.  Even though NTFS can go much longer...  Very confusing.  Isilon has it's own limits: Filename length is 255 bytes. Path length limit is 1024 bytes, the maximum length that can be passed into a syscall,  but not the maximum depth of a directory in the filesystem. Directory Depth is theoretically unlimited, but things start to break at 8470; thus that is the recommended limit.  Does that answer your question?  Cheers,Matt
I consistently get questions and concerns around file path name limitations in relationship to SMB.  According to NTFS specifications the max TOTAL path length is actually 32,767 unicode characters—which is approximate depending on prefix expansion.  While I understand the MAX_PATH is 260, this refers to each component in the  \\server\share\directory\directory\directory\...\filename structure which are commonly limited to 255.So is this a Posix Unicode limitation on Isilon or a Microsoft specific limitation?
Path Name Limitation