Protocol Specific Port Page (SPC3)

Mike Berhan mikeb at
Mon Nov 4 09:25:38 PST 2002

* From the T10 Reflector (t10 at, posted by:
* "Mike Berhan" <mikeb at>
I have been sent trace information from an IBM IC35L146UCDY10-0 SCSI
Disk Device.  This is a U320 drive.  The CDB being sent to the drive is
a Mode Sense - Protocol Specific Port Page.  CDB follows:

5A 08 19 00 00 00 00 80 00 00

The drive returns the first 8 bytes as the mode page header which is
valid.  Following the header is the protocol specific port page data.
The first three bytes in this page are:

99 06 00

In looking at the SPC3 R9 specification, the Page_0 format Protocol
Specific Port mode page is defined as follows:

Byte 0: PS, SPF, and then Page Code of 19h in bits 0-5
Byte 1: Page Length (n-1)
Byte 2: Reserved from bits 4-7, Protocol Identifier in bits 0-3
Bytes 3-n:  Protocol Specific Mode Parameters

In looking at the first three bytes of 99 06 00, I do get the page code
of 19h (SPF=0), a page length of 6, and a protocol identifier of 0.  In
Table 235 of the specification, it defines a Protocol Identifier value
of 0 to be Fibre Channel (FCP-2).

Question:  Should the device have returned a protocol identifier of 1h
(Parallel SCSI) or am I not interpreting the specifications properly?

Thank you in advance.

Mike Berhan

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