[Info-vax] RMS record metadata, was: Re: Re; Spiralog, RMS Journaling (was Re: FREESPADRIFT)

[David Froble]

Simon Clubley wrote:
> On 2016-06-18, Paul Sture <nospam at sture.ch> wrote:
>> On 2016-06-18, Stephen Hoffman <seaohveh at hoffmanlabs.invalid> wrote:
>>
>>> Do you count that metadata in the file size, or not? Arguably no, but
>>> it's inherently part of the file on OpenVMS and not at all easy to
>>> exclude — whether VFC or the indexed file structures or otherwise.
>> Tricky.  If you are looking at the output of TYPE, then the record
>> attributes (e.g. Record attributes Carriage return carriage control)
>> make a difference to the output.
>>
> 
> IMHO, it depends on the context. If you are doing block level reads,
> then you count the size of the on-disk metadata in the file size.
> 
> If you are doing record level reads, then you do not include the
> metadata IMHO but you _do_ add in any additional terminator bytes to
> the length (which might not actually be stored on disk).
> 
> You need the former if you are doing an image copy. You need the latter
> if you want to tell a webserver at which point it should resume the
> download.

Hmmm ...  Never considered that.  Then again, for most HW, you're probably going 
to read and write whole blocks anyway.  If I was solving the problem, which I'm 
not, I do think that I'd re-start on block boundaries.

> Also, IMHO I think the default sequential record type for today's
> world should be stream (and hence the terminator is also included in
> the file data.) I do not think it should be variable length records.

I'm still thinking about that one.  Perhaps I'm blinded by past expectations.

> The problem is that today's protocols are simply not designed to
> handle the case of metadata buried within the file contents
> themselves; the people who design this stuff have probably never
> even encountered that case.

Perhaps we need different designers ???

:-)

> I do wonder how the IBM mainframe people handle this problem.

However they want, and I'm sure they don't care about other environments ..