about Storage Enclosure Processors in SAS-1.1

Elliott, Robert (Server Storage) elliott at hp.com
Mon Dec 8 13:36:57 PST 2003

* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <elliott at hp.com>
> * From the T10 Reflector (t10 at t10.org), posted by:
> * "Shogo Hamasaku" <hamasaku at d1.hw.necst.nec.co.jp>
> *
> Hi all,
> I think about the directly connectable Storage Enclosure 
> Processors (SEP) which has SAS interface as follows.
>   a) The SEPs are wasteful with a SAS port.
>   b) It takes several years that the SEPs are released.
> Now SATA-2 standard provides the bridge between SATA and I2C. 
> It is called SATA Enclosure Management Bridge (SEMB).
> I thought it is economical that the expander has a bridge function 
> like SEMB. Do you have any plan like that in SAS standard?
> Thanks,
> Shogo Hamasaku
> NEC System Technologies, Ltd.
> External:(+81)89-947-7901

An expander may contain an embedded enclosure management processor.

Architecturally, this is represented as an expander device that 
contains an internal SAS device that contains an internal SAS port 
(see sections 4.1.1 and 4.1.5).

The internal SAS port has its own SAS address, and is "attached to"
a virtual phy in the expander device.  If the expander has 16 external
phys, the 17th phy would be a virtual phy "attached to" the enclosure
management processor.

If the internal SAS port uses SSP protocol, then the enclosure
management processor can serve as a SES-2 (SCSI Enclosure Services 
command set) logical unit.

Alternatively, the internal SAS port could speak STP protocol and 
implement the the SEP_ATTN command and other SEMB features defined 

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

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