Questions on SES specification -> Enclosure Logical Identifier (ELI)

Elliott, Robert (Server Storage) Elliott at
Thu Dec 22 16:57:37 PST 2011

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Fibre Channel JBODs supported an "attached enclosure services process" model
where a disk drive provided the SCSI target port and the SCSI device server,
and the drive communicated with the enclosure services process over the
Enclosure Services Interface (ESI) pins on the SCA-2 connector (SFF-8067).  A
JBOD might support ESI in multiple drive slots, allowing multiple management
paths to the same enclosure services process.  The ENCLOSURE LOGICAL
IDENTIFIER field helps identify that the same enclosure services process has
been reached regardless of the path (e.g., like how the logical unit name in
the Device  Identification VPD page is used by multipathing software).
Rob Elliott    HP Server Storage
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Raj Divecha
Sent: Tuesday, 20 December, 2011 7:01 PM
To: t10 at
Subject: Questions on SES specification -> Enclosure Logical Identifier (ELI)
Mostly all old and new specifications of SES (2r20) mention that ELI shall be
unique to a subenclosure and may be different from the WWN of the LU
providing the enclosure services. As far as the definition is concerned, it
simple to understand. However, I am not able to make out the purpose of
having an ELI. I tried looking in SPC (4r12) but didn't found any reference.
I then looked in SPL (r07) and found a reference which pointed to the
definition in SES. Thus, I am not getting any clear idea about its use or its
purpose. I am assuming that it would help to consolidate enclosure
information coming from more than one Enclosure Services Process (ESP). Is
this assumption correct and is it the only purpose?
Can the SES specification elaborate on the purpose of ELI?

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