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Method for Intrasystem and Intersystem Unique Host Identifiers Disclosure Number: IPCOM000030928D
Original Publication Date: 2004-Sep-01
Included in the Prior Art Database: 2004-Sep-01
Document File: 2 page(s) / 70K

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A method for creating Intersystem Unique Host Identifiers for zArchitecture Machines is described.

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Method for Intrasystem and Intersystem Unique Host Identifiers

World wide unique intersystem host identifiers (path group identifiers, PGID) are required for each operating system image that channel attach devices using the Enterprise Serial Connection Architecture (ESCON) or the Fibre Channel Connection Architecture (FICON).

Path Group Identifier Algorithm

    Intersystem host identifiers are eleven bytes in length and are constructed from the high order four bytes of the time of day clock (TOD) and the data returned by the store-id-processor (STIDP) instruction as follows:

The data returned by STIDP contains the following information:

Byte 0, bits 0-1, the high order two bits, are used as a new format identifier:

B'00' designates that the PGID was constructed with the original PGID



algorithm created in 1979.

B'01' designates the new PGID algorithm where the second byte contains the



B'10' is reserved for future use

B'11' is reserved for future use


Byte 0, bit 4 indicates when the PGID was created by a hipervisor Byte 1 is set to the channel subsystem identifier (CSSID)

Bytes 2 to 10 of the PGID contain STIDP data as follows:


The six digit CPU serial number, which include a one byte logical partition


identifier (LPAR ID)

High order four bytes of the TOD clock


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Path G roup Identifiers

B yte 0 2 5 8

S T A P L P n n n n T yp e T O D C lo c k

Left hand 4 bytes from


B yte 0 1 2 5 8

ff--v--- C S P P n n n n T yp e T O D C lo ck