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Comment by malkia | Hacker News Reader

So what are the features that OpenVMS has that others do not have? (Just curious)

Like most things you have to bear in mind the time context - VAX/VMS had robust clustering of a solid multi-user, OS pre-1990. That was before Linux, the first release of SunOS and before Windows had networking.

The versioning filesystem is very nice - better than snapshotting, it's as though the whole system were under version control, and it's integrated with the whole OS.

Performance and security were reputedly very good, though I've no idea how it's kept up these days.

I've never used it but I read a lot of accounts of superb clustering capabilities. You can have clusters spanning several OS releases on different hardware platforms.

I can’t find the original source but I remember reading an article about a VMS cluster that was moved piecemeal between two towns in Belgium without any downtime. Individual machines went down during the move obviously, but the cluster as a whole was able to stay up.

I remember this - I thought it was on el reg, but worse, it was theinq :)

https://web.archive.org/web/20031219162954/http://www.theinq...

Wow, so it was. Takes me back :) Thanks for digging it up! Here’s the source story: http://www.openvms.org/stories.php?story=03/11/28/7758863

Clustering on VMS is mostly about marketing and integration, VMS cluster is essentially only about shared filesystem and same effect can be had by means of NFS and some kind of centralized management on Unix (even across different Unix OSes). It does not do any magic like process migration and intra-cluster shared memory.

From technical standpoint interesting feature is sane approach to asynchronous IO and IPC (think libevent in kernel).

There is nothing "only" about a clustered shared filesystem.

There may be a hundred of them but none works off the shelf for all applications. There are a lot of details in there.

You could probably make the point that early Google was "only" a clustered filesystem plus some apps running on top on it.

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