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Re: ROOT file_ids and Bundle_ids
"David M. Malon" wrote:
> > In the long run, we'd like to have the Storage Manager software
> > unafected by the type of files we deal with - Objectivity files, ROOT
> > files, or any other kind. To accommodate that, we'll have to use a
> > consistent set of file_IDs, regardless of where they come from. I'll
> > elaborate on how we plan to do that later.
> > As for what we pass to the Event Iterator (EI) for multiple components,
> > we concluded that we'd like to pass a bundle_id, and when the EI is
> > done with the bundle, it should use this bundle_id when releasing the
> > bundle. However, if there is a value to passing the file_ids (or
> > file_names) we could do that also at a later time (after MDC2).
> > So, here is what we plan for MDC2 and after MDC2.
> > For MDC2:
> > 1) Both Objectivity files and ROOT files will be pre-assigned
> > Objectivity file-ids, and those will be used by the index.
> I expressed my concerns last month about faking Objectivity into
> generating db numbers as fileids for ROOT files, and I thought that
> Doug and Torre, among others, shared my concerns. By the way,
> implementing that deception may involve some subtleties.
I thought this was a done deal for MDC2. I.e., that we agreed upon using
the Objectivity catalog for ROOT files. Are you saying that is is a bad
idea even for MDC2?
> My understanding is that David Zimmerman is working on a method for
> generating consistent fileids for ROOT and Objectivity files, with
> a simple interface for use by Storage Manager components to translate
> from ids to names. If he does not have time for this, I will volunteer
> to do it.
> > 2) All file names (including path_names if more that a single
> > directory is used) will be retrieved from the Objectivity catalog.
> I would be happier if we could amend this to say "will be retrieved
> from the Objectivity federation."
> > 3) We assume files can be in different directories. However, the same
> > directory structure will exist beyond a root-path in HPSS as in Unix.
> > (e.g. suppose the Objectivity root-path is o1/o2/o3 and HPSS root-path is
> > h1/h2, then a file in Objectivity directory o1/o2/03/x/y/z/file_name,
> > will be in the HPSS directory as h1/h2/x/y/z/file_name.) Thus, given the
> > objectivity path, the HPSS path can be generated.
> I'm not sure I understand this. Do you mean that I can have an
> arbitrary number of prefix pairs:
> o1/o2/o3 corresponds to HPSS h1/h2
> o1/o2/o4 corresponds to HPSS h1/h3
> o1/o5/06 corresponds to HPSS h1/h4
> o7/o8 corresponds to HPSS h5/h6/h7
> or that I can have only one, so that the HPSS directory structure
> must (after substituting prefixes) precisely mirror the disk directory
Yes, you can have only one. That simplifies the work of the Cache Manager much.