Memories are made of NIS

I was reading this article about the potential removal of the NIS (Network Information System) component from Fedora systems. It reminded me of an old experience managing our department’s systems.

Our development team was very early in working with AIX systems. We were writing kernel (and micro-kernel) code for the IBM RT, a predecessor to the RS/6000 and Power systems. We needed a shared environment so that we could all log on to any free machine in our group (not enough for one each), and access all our files.

Fortunately, IBM had a product solution for AIX that should help. Known as Distributed Services, it had file-sharing and user/group-sharing across a network. And it was based on SNA LU6.2 protocols, to ensure reliability and security. None of that cheap TCP/IP nonsense. But as anyone who has ever worked with SNA knows, that comes with a severe cost in usability, especially in configuration. Once it works, it works fine; but getting it to that stage can take a huge amount of planning, to ensure that every option at each level of the protocol (Node, Control Point, LU …) matches. I’ve just pulled up the GUI configuration for SNA on my current AIX system to be reminded of the horrors. Although MQ still has support for SNA channels, and it continues to be tested, I don’t know if anyone actually understands it.

We struggled through getting Distributed Services and all its underlying pieces configured for a couple of days, but were finally ready to turn it on for a pair of boxes. And whatever we’d done, it managed to wipe out the /etc/passwd and /etc/group files on the machines. Both turned to zero bytes long, making the machines unusable. Rather than go back and work out what we’d done wrong, we decided to try the alternative solution that we’d spotted – a combination of Yellow Pages (as NIS was still called at the time) and NFS. Even though it was not the officially-blessed product. Within half an hour, starting from no knowledge, and with no search engines to assist, just reading the documentation, we had a working environment. And that survived for many years.

If Distributed Services had done what I’m sure it COULD do when properly configured, then we’d never have learned about what were, for many years, key pieces of technology in the management of Unix machines. While NIS is not part of my current environment, I still miss some aspects of it – in particular synchronisation of the uid/gid numbers across machines that simplify a bunch of processes. I have been 6505 for a lot of years and a lot of machines, even when I need to manually edit system files to keep that number.

This post was last updated on November 11th, 2021 at 11:07 am

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