HPSS classes of service

["Craig E. Tull" <cetull@lbl.gov>]

I fear I was spreading blatant falsehoods at the Objectivity Quick Start
Class. 

According to our NERSC HPSS experts, a single file can only belong to one
HPSS class of service at a time. Moving a file between two classes of
service implies a physical copy of the file from one tape to another.

This means that the scheme of accessing an Objectivity database file
through two distinct channels:

	1> the Storage Manager class of service
		(with most of the tape drives and disk cache)
	2> the "rouge pointer" class of service

would not be possible.

- Craig

-----------------------------------------------------
 Craig E. Tull, Ph.D.
 National Energy Research Scientific Computing Center
 E.O. Lawrence Berkeley National Laboratory
 EMail: cetull@lbl.gov       WWW: iago.lbl.gov/~tull
 Phone: (510)486-7253        FAX: (510)486-4004