[Info-vax] Current VMS engineering quality, was: Re: What's VMS up to these

[glen herrmannsfeldt]

Johnny Billquist <bqt at softjar.se> wrote:

(snip)
> 1. VMS clusters did not use ethernet originally.
> 2. Unix distributed networks using ethernet and shared disks is not 
> robust at all. You must be totally uninformed if you claim this. Have 
> you ever used a machine with an NFS root? Any time the server stopped, 
> rebooted, or whatever, all clients *freeze*. Not even rebooting, unless 
> you press the power switch. You just sit there waiting for the NFS 
> server to wake up again.

I haven't done it for a while, but most often you can reboot without
accessing the specific disk.

> 3. Unix, using NFS, is weird and unreliable. File locking does not work 
> properly. 

In general, Unix doesn't do much file locking, and, yes the NFS
implementation is especially troublesome.

> File renaming and deletion is troublesome, and deleting a file 
> used over NFS is handled by actually not deleting the file, but instead 
> renaming it to something starting with a period, so that you don't 
> normally see it, creating the illusion that you deleted the file. 

That should only happen if the file is open when you delete it.
The client should then delete the file when it is closed. If the
client crashes before it gets to close it, the file won't be delete.

Unix convention is that if you delete an open file, it stays around
until closed, though the name is removed from the directory.
It isn't possible to do that with a stateless NFS server.

> Furthermore, security wise, it is a joke. You use mountd daemon to mount 
> and access NFS disks, but if you know the file handles, you can totally 
> skip the mounting, and thus also skip the permissions of the 
> /etc/exports file.

I thought it was supposed to be better now, but it is best for
local networks where you trust the users.

> 4. Unix does normally not crash, but instead freeze. And not only if the 
> network goes down, but also if the single machine serving the disk goes 
> down. Also, if anything in the server configuration changes, all clients 
> needs to be rebooted, no matter if the server comes back, since NFS 
> don't allow any recovery in that case. And we are talking about very 
> ungraceful rebooting here. No controlled take down. You'll have to reach 
> for the reset or power switch, since controlled shutdown is impossible.

I am not sure exactly how much has to change. If something relating
to the specific disk changes, then yes. 

I once sold a server while clients still had the disk mounted.
If you are fast, you can umount before the disk is accessed, but
otherwise, yes, reboot is the only way.

(snip)

> Go back to playing with Windows, and stop posting to this newsgroup, 
> since you obviously have little to contribute anyway. And VMS and DEC 
> bashing in general is not classified as "contributing".

There used to be free from MS an NFS client and server for NT
and NT based systems. I am not sure about Vista and later.

-- glen