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I know it's always hard to define an exact first, so I'll just ask about early network file systems. To be more specific, I'm wondering about file systems that transparently present directories and files as if they were local. I don't consider FTP or similar mechanisms to be candidates.

For some time it has been my suspicion that the ITS "MLDEV" facility was very early ("the first"), but I never had any facts to back it up. I do have a file timestamped November 1972 that gives us an upper bound for the introduction of the facility. On the MIT-AI PDP-10, it provided an ML device (hence the name) which worked much like the local DSK device except the data was accessed through MIT's ARPANET IMP. MIT-ML of course had an AI device.

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    How do you define "transparently ... as if they were local"? – Jeff Zeitlin Feb 11 at 18:31
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    What do the acronyms "ML" and "AI" stand for? – snips-n-snails Feb 11 at 18:47
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    I'm hoping this doesn't evolve into a discussion about the exact definitions (which will never settle) of what constitutes network or transparency. I'd rather people decide for themselves and describe the technology. – Lars Brinkhoff Feb 11 at 19:14
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    @snips-n-snails, AI means artificial intelligence, specifically MIT's AI lab, and ML means mathlab. – Lars Brinkhoff Feb 11 at 19:16
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    Investigate The Cambridge Ring, the Cambridge File Server and WFS at Xerox PARC. – Alan B Feb 12 at 14:04
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Present evidence is that ITS had a very early networked file system no later than 1972.


ITS has had a facility called the "ML Device", or MLDEV, for a long time. The name probably comes from a time when the users of the older more established computer called AI wanted access to files on the computer called ML. The "device" part is because ITS files are named by four parts: device, directory, and two file names. To access ML files from AI, the device name is ML. Conversely, from ML the AI device is used.

To date this facility, we can check timestamps from backup tapes. The earliest file called MLDEV is from July 1975. However, if we examine the source code for an earlier ITS version we see that it has built in ML and AI devices that when accessed starts a program called SYS; ATSIGN OTHER. Disassembling this file we can see that it indeed is accepting file operations and sends information across ARPANET. The earliest file with that name has a timestamp from November 1972.

We know from RFC documents 342, 344, and 366 that AI and ML were first put on the ARPANET in May-June 1972. So MLDEV could not have been in use before 1972.

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