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Method to Provide Consistent Device Names and Addresses Across Reboots on Magnum/Draco Hardware

IP.com Disclosure Number: IPCOM000012672D
Original Publication Date: 2003-May-20
Included in the Prior Art Database: 2003-May-20
Document File: 6 page(s) / 59K

Publishing Venue

IBM

Abstract

Enabling I/O partitioning via partition control facility is disclosed.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 18% of the total text.

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  Method to Provide Consistent Device Names and Addresses Across Reboots on Magnum/Draco Hardware

  A NUMA-architected computer system comprises one or more "quads" of computing elements, each quad containing elements such as CPU/memory/IO devices etc. (The name quad derives from the presence of four CPU's per computing element which is common , but not necessary, in NUMA systems.) The quads may be bound into groups, called partitions, that host a single instance of an operating system (OS). Each partition, comprising one or more quads, hosts an independent instance of an operating system. These instances don't share any of the computing elements, e.g., CPUs/memory or I/O interfaces. It is possible to, statically or dynamically, reconfigure the machine into alternative partitions. Static partitioning requires the operating system instances to be shutdown. Dynamic partitioning implies OS involvement since the OS must relinquish memory, move its processes to in-partition quads and stop using existing I/O, e.g., network and storage connections. It may additionally attempt to move all communications to in-partition I/O interfaces. Repartitioning imposes certain requirements on I/O resources. This document presents a design to meet these requirements in an OS independent way. This discussion focuses on the following requirements:
1. the OS must have access to same I/O resources across reboots
2. consistent device names for a OS image regardless of hardware partition the system is executing on
3. consistent host name and IP address(es) across reboots
4. A form of partitioning is wherein the OS is rebooted on some of the original quads or on an entirely different set of quads. The OS image is the same but the hardware partitioning is different.
5. All effort must be made so that the OS implementation (Linux*, Windows**, AIX ***, etc.) changes little, ideally none at all. In all these circumstances the OS must behave exactly as if it was rebooted on a standalone system with no partitioning. A common refrain in the above requirements is device identification. Unless one knows the devices in a partition one cannot ensure their availability in any reconfigured partition. Unless the devices are identified unambiguously one cannot assign them names or ensure that the names are consistent across reboots and repartitions.

  A unique value associated with the device will allow unambiguous identification of a particular device if this value is also invariant and accessible. This value can further be used as the key into a database that records the name or label assigned to the device by the OS. Finding a unique value may be as simple as reading a universally unique identifier (UUID) off the device. For example, disk drives carry unique labels. Even if the labels are not unique across all drives the vendor ID and model number can be used to create a unique identifier for the drive. The identifier is invariant and the system can always uniquely identify the d...