5 ms·

What are the things VMS did the best? How it compares to linux nowadays? What is behind OpenVMS project - nostalgia or some pragmatic reasons?

yellowapple 7y ago
The more relevant point of comparison would actually be Windows, given the extensive design similarities between Windows NT (and thus, by descent, modern Windows) and VMS: https://everything2.com/title/The+similarities+between+VMS+and+Windows+NT https://everything2.com/title/The+similarities+between+VMS+a...
- snagglegaggle 7y ago
  A lot of modern Windows kernel API looks exceedingly familiar to Unix. I would think perhaps early Windows was close to VMS, but as they tried to bolt on a POSIX layer it seems it has drifted. Features of VMS like transparent clustering are missing, for example.
  - abotsis 7y ago
    Which api’s specifically? VMS was always (and still is?) posix compliant, as was nt. VMS even ran x11!
    - wbl 7y ago
      The I/O model in the kernel is very similar and utterly unlike Unix.
      - snagglegaggle 7y ago
        As you move up the stack it looks more Unixy. The core is VMS-like and I can see the similarity, but it seems to me the majority of the code actually written exists in a middleware layer that is maybe not as far from VMS as Linux, but not quite VMS. Names can be quite different. I remember looking at the disk stack and thinking it looked quite similar, save for completion ports.
        wbl 7y ago
        Softirq and taskqueue change the model to be more VMS like.
  - pjmlp 7y ago
    Window kernel APIs have nothing UNIX like beyond sockets. POSIX personality was the place for them. Modern Windows follows mainframe's footsteps by providing UNIX compatibility via a VM environment.
LinuxBender 7y ago
Best? Stability. (In my opinion and experience) I never saw OpenVMS crash. I was never paged for an OpenVMS / Alpha system being offline.
- eej71 7y ago
  I have. Lots of times. Depends on what abuse you heap on them. And yes, been paged for nodes crashing, hung clusters, etc.
eej71 7y ago
The pragmatic reason is that there are enough organizations out there that depend on it and porting away from it is expensive enough that it is cheaper to stay.
goatinaboat 7y ago
It’s still unmatched for seamless language interoperability. vMotion is a sort of crude version of VMS live process migration between nodes. The security model is very well thought out, beats rwxrwxrwx and setuid hands down. Versioning filesystem, and RMS means the filesystem is a simple database too. DCL seems weird but all the commands work the same way, take the same arguments and so on. You can guess with a very high chance of being right. And if you can’t the help/error message is actually useful. Rock solid stability. Generally very easy to manage, one sysadmin can do a lot.
- pjmlp 7y ago
  Even when comparing against IBM i and z/OS language environments? What about Windows CLR/COM/UWP? Curious about what you find being unmatched, as I never used VMS, beyond diving into its developer's documentation.
- zvrba 7y ago
  > It’s still unmatched for seamless language interoperability. I don't know about how it works on VMS, but Microsoft's COM is the only other attempt of language interop I know of. Recently I implemented a COM server, added `IDispatch` to its interfaces and suddenly I could control and test it from Porwershell with no extra effort on my part. Like, magic.
  - goatinaboat 7y ago
    I’ve used COM (and before that CORBA) but these operate at a different level of abstraction. On VMS calling a Pascal function from FORTRAN “just worked” and then you could pass the return value to a C function or BASIC and it was fine. VMS IPC was done via mailboxes, send a message to a person or a program was the same. Which sounds weird to anyone used to the way Unix does mail, but it worked very well. (Yep, VAX BASIC was a serious language used for real, production applications)
turk73 7y ago
Nothing, really. The world moved on but a lot of fanbois didn't. I learned to code C on a VT420 and used VMS for quite a few years, many professionally. I never felt it was anything superb at all. As soon as I learned UNIX (and I've used every brand and flavor of it), there was just no comparison at all. SunOS and later Solaris were my favorite until Linux matured.

yellowapple 7y ago

The more relevant point of comparison would actually be Windows, given the extensive design similarities between Windows NT (and thus, by descent, modern Windows) and VMS: https://everything2.com/title/The+similarities+between+VMS+and+Windows+NT https://everything2.com/title/The+similarities+between+VMS+a...

snagglegaggle 7y ago
A lot of modern Windows kernel API looks exceedingly familiar to Unix. I would think perhaps early Windows was close to VMS, but as they tried to bolt on a POSIX layer it seems it has drifted. Features of VMS like transparent clustering are missing, for example.
- abotsis 7y ago
  Which api’s specifically? VMS was always (and still is?) posix compliant, as was nt. VMS even ran x11!
  - wbl 7y ago
    The I/O model in the kernel is very similar and utterly unlike Unix.
    - snagglegaggle 7y ago
      As you move up the stack it looks more Unixy. The core is VMS-like and I can see the similarity, but it seems to me the majority of the code actually written exists in a middleware layer that is maybe not as far from VMS as Linux, but not quite VMS. Names can be quite different. I remember looking at the disk stack and thinking it looked quite similar, save for completion ports.
      - wbl 7y ago
        Softirq and taskqueue change the model to be more VMS like.
- pjmlp 7y ago
  Window kernel APIs have nothing UNIX like beyond sockets. POSIX personality was the place for them. Modern Windows follows mainframe's footsteps by providing UNIX compatibility via a VM environment.

LinuxBender 7y ago

Best? Stability. (In my opinion and experience) I never saw OpenVMS crash. I was never paged for an OpenVMS / Alpha system being offline.

eej71 7y ago
I have. Lots of times. Depends on what abuse you heap on them. And yes, been paged for nodes crashing, hung clusters, etc.

eej71 7y ago

The pragmatic reason is that there are enough organizations out there that depend on it and porting away from it is expensive enough that it is cheaper to stay.

goatinaboat 7y ago

It’s still unmatched for seamless language interoperability. vMotion is a sort of crude version of VMS live process migration between nodes. The security model is very well thought out, beats rwxrwxrwx and setuid hands down. Versioning filesystem, and RMS means the filesystem is a simple database too. DCL seems weird but all the commands work the same way, take the same arguments and so on. You can guess with a very high chance of being right. And if you can’t the help/error message is actually useful. Rock solid stability. Generally very easy to manage, one sysadmin can do a lot.

pjmlp 7y ago
Even when comparing against IBM i and z/OS language environments? What about Windows CLR/COM/UWP? Curious about what you find being unmatched, as I never used VMS, beyond diving into its developer's documentation.
zvrba 7y ago
> It’s still unmatched for seamless language interoperability. I don't know about how it works on VMS, but Microsoft's COM is the only other attempt of language interop I know of. Recently I implemented a COM server, added `IDispatch` to its interfaces and suddenly I could control and test it from Porwershell with no extra effort on my part. Like, magic.
- goatinaboat 7y ago
  I’ve used COM (and before that CORBA) but these operate at a different level of abstraction. On VMS calling a Pascal function from FORTRAN “just worked” and then you could pass the return value to a C function or BASIC and it was fine. VMS IPC was done via mailboxes, send a message to a person or a program was the same. Which sounds weird to anyone used to the way Unix does mail, but it worked very well. (Yep, VAX BASIC was a serious language used for real, production applications)

turk73 7y ago

Nothing, really. The world moved on but a lot of fanbois didn't. I learned to code C on a VT420 and used VMS for quite a few years, many professionally. I never felt it was anything superb at all. As soon as I learned UNIX (and I've used every brand and flavor of it), there was just no comparison at all. SunOS and later Solaris were my favorite until Linux matured.