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

[Jan-Erik Soderholm]

glen herrmannsfeldt<gah at ugcs.caltech.edu>  wrote:

>
>>> IBM can do this stuff correctly, UNIX can't. UNIX and NFS
>>> are broken, this is just one of a million stupid UNIX non-designs.
>>
>> What does IBM do? On which system?
>
> IBM shares DASD in a sysplex, across multiple physical machines, with full
> integrity. Standard on MVS at least since ESA (circa 1987) maybe earlier.
>
>>>> Why would you expect that in the case of an NFS disk?
>>
>>>> As previously mentioned, the result is data loss.
>>
>>> Two phase commit. Don't depend on clients and servers to always get
>>> along, plan for the times they don't. Don't lose data. Don't hang
>>> a client machine. It's all basic, obvious stuff for a serious OS.
>>> UNIX needs work, lots and lots of work.
>>
>> I suppose you could return a fatal write error to the client program,
>> which pretty much means data loss. How many programs have a way to
>> handle a write failure by writing the data somewhere else?
>

The importent thing here is to be able to detect a failed write at
all, to log it and maybe report it back to some human user at the
terminal/browser or whatever. And also make sure that any other update
that is part of the same "transaction" is handled in a proper way
(usualy rolled back).

The user then can take propar action and switch to some backup routine,
redo the operation at a later time or whatever is appropriate.

A data loss as such doesn't have to be a major problem, if it is known.