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

[Simon Clubley]

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.

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.

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.

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

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
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