SES-2 Page 0x0A clarification

Elliott, Robert (Server Storage) elliott at
Tue Nov 23 17:32:38 PST 2004

* From the T10 Reflector (t10 at, posted by:
* "Elliott, Robert (Server Storage)" <elliott at>
-----Original Message-----
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Samer
Sent: Monday, November 22, 2004 6:07 PM
To: t10 at
Subject: SES-2 Page 0x0A clarification

> in ses2r09
> Section 6.1.13 defines the Device Element Status diag page.
> Imagine a 12 Phy expander with 4 drives attached, one
> 4-wide port attached to an initiator, and another 4-wide
> port to a down-stream expander.
> The question is how do the Device Element Status
> descriptors look like?
> From
> Are there six element descriptors (ignore other elements
> for now): four for the drives, and one for each of the
> Initiator port, and the expansion port to the next
> expander.

Are the initiator and downstream expander located in the enclosure being
managed by this SES, or are they attached via a connector?  If they are
not in the enclosure, then they shouldn't be represented as elements.

If the initiator is in the enclosure, it could be represented with a
SCSI Initiator Port element (15h).  I don't think a Device element is a
good match; I think of those as being for disk drives in bays.  SES
adopted the "Device" name before SAM-2/SAM-3 cleaned up device/port
terminology, so it might be a bit misleading nowadays.  

The SCSI Initiator Port element doesn't have corresponding Device
Element Status information, though.

If the expander is in the enclosure, then see proposal 04-374, which
proposes a new SAS Expander element (so the Device element doesn't have
to be used for an expander).  Note that 04-374r0 was just the initial
draft, and r1 will have significant changes based on WG feedback two
weeks ago. 

> If the element descriptor is associated with a wide port,
> then the NOT ALL PHYS bit will get set whether all Phys are
> included in the descriptor or not. If the port being
> described is narrow, then the NOT ALL PHYS bit = 0, and
> their is only one Phy descriptor.

NOT ALL PHYS=1 was included in case the SES doesn't know about all the
SAS addresses of the managed device.  For example, in a dual-domain
enclosure, an SES in one domain might not know the address of the disk
drive phys in the other domain.

If there are multiple phys in a wide port (in the same domain as the
SES), their SAS address must be the same, and SES should know about all
of them.

> Thank you,
> Samer
> --
> Samer A. Haija (samer at
> Vitesse Semiconductor Corporation
> Ph: (719) 867-6267
> Fax: (719) 867-6203  

Rob Elliott, elliott at
Hewlett-Packard Industry Standard Server Storage Advanced Technology

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