99-230r0 - Extended Copy Support for Persistent Reservations

Ralph Weber ralphoweber at CompuServe.COM
Sat Aug 21 06:09:10 PDT 1999


* From the T10 Reflector (t10 at t10.org), posted by:
* Ralph Weber <ralphoweber at compuserve.com>
*
A proposal for consideration at the September meetings has
been placed on the T10 FTP site as:

< ftp://ftp.t10.org/t10/document.99/99-230r0.pdf >

The complete proposal appears only in the PDF file.  An
overview of the proposal is as follows:

Doc:  T10/99-230r0
Date: 15 August 1999
To:   T10 Technical Committee
From: Ralph Weber, LSI Logic Alternate Member of T10
Subj: Extended Copy Support for Persistent Reservations


Third-party reservations were invented to support the COPY command.
So, what's being done to match the new reservations paradigm to
EXTENDED COPY?  This proposal attempts to address that question.

Unlike RESERVE/RELEASE, persistent reservations are designed to
support concurrent sharing of a device by multiple initiators.  Thus,
persistent reservations need no additions to support EXTENDED COPY.
However, an addition is required in the EXTENDED COPY command
definition.

The complete document in the PDF file proposes the definition of a
new EXTENDED COPY Segment Descriptor that instructs the copy manager
to register a specified reservation key with a specified copy target
device.  Note: the copy manager is not instructed to make or preempt
a persistent reservation, only to register a key.  By using a
Registrants Only reservations and preempting previous registrations
by the copy manager, the initiator can create an environment where
registering a reservations key is the only action a copy manager need
take.




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