[Go-essp-tech] versions, checksums and the TDS

[Estanislao Gonzalez]

I recall a problem that when altering the file with some tools (cdo?) 
the tracking id wasn't automatically changed.
Are we sure that the same tracking id point to the same file now?
Is the previous not a problem anymore?

Thanks,
Estani
Am 24.09.2011 18:17, schrieb Karl Taylor:
> Dear all,
>
> Concerning:
>
> On 9/24/11 4:35 AM, Estanislao Gonzalez wrote:
>> 2) checksums
>> They are the only reference to the outside that a data node give of the
>> changes a file suffered from one version to another, i.e. for
>> replication we use that information to retrieve only files that change
>> from one version to another. The same principle could be applied for
>> tools designed for end users.
>
> without disputing that checksums should be mandatory, I want to point 
> out that a user who has lost the checksum associated with a file he 
> has downloaded shouldn't have to recompute the checksum to determine 
> whether his file is a copy of a file residing at the datanode.  Recall 
> that recorded in each netCDF file is a unique tracking_id, which I'm 
> almost positive is also in the thredds catalog.  It will certainly be 
> quicker for the user to read the tracking_id and then check whether it 
> matches the latest version.  I think we want to maintain tracking_id 
> as an option for checking whether new files exist in a new version.
>
> best regards,
> Karl


-- 
Estanislao Gonzalez

Max-Planck-Institut für Meteorologie (MPI-M)
Deutsches Klimarechenzentrum (DKRZ) - German Climate Computing Centre
Room 108 - Bundesstrasse 45a, D-20146 Hamburg, Germany

Phone:   +49 (40) 46 00 94-126
E-Mail:  gonzalez at dkrz.de

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