Assumptions we'll rely on for MDC2

[Arie Shoshani <arie@math.lbl.gov>]

We discussed the various requirements for the Storage Manager 
components for MDC2, and want to make explicit the assumptions we 
are relying on.  This is mainly to verufy that we all agree on 
these assumptions.

1)  Each event header will contain information about the event 
components.  Thus, in response to a multi-component request from an 
EI, it is sufficient for the Storage Manager to return only the 
event_oids list.  The user code will get the OIDs for each 
component from the event header.

Note: as explained in my last message the response to a request 
from an EI has the form:

[file_c(i), file_c(j), ...]: {list of event_oids},

where file_c(i) is the ID of a file for component i that contains 
all the event components in the {list of event_oids}.  Similarly, 
for file_c(j), etc.  

We call [file_c(i), file_c(j), ...] a file bundle.  There are 
multiple file bundles for each multi-component query, where some 
files may appear in multiple file bundles.

2)  A response to a multi-component request will be made only after 
all the component files were cached.  

3)  For component files that are not stored in Objectivity, there 
will be an empty directory in Objectivity.  Thus, each 
non-objectivity file will have a file_oid, and its names can be 
gotten from the objectivity directory, just as for Objectivity 
files.

4)  Files can be stored in multiple directories.  Thus, for each 
PFTP the file location (path) will be determined dynamically.

5)  The cache (using multiple disks) will be managed by a 
multi-disk file manager (such as veratose).  Thus, the entire cache 
will be viewed as a single cache by the Storage manager.

Comments?

Arie.