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Method and Apparatus For Setting The Initial State Of A Resource

IP.com Disclosure Number: IPCOM000028895D
Original Publication Date: 2004-Jun-07
Included in the Prior Art Database: 2004-Jun-07
Document File: 1 page(s) / 45K

Publishing Venue

IBM

Abstract

When multiple systems share common resources, it is often necessary to set the initial state (or configuration) for those resources. In an environment where the resources are not shared, this is typically done during system initialization (or boot time) by setting the state of the resource to some state which was predetermined by a system administrator. However, in an environment where the resources are shared, it is possible that dynamic commands have been issued by systems which are still active which have modified the state of these shared resources. In this case, if a system were to set the state of a resource to some predetermined state when it initializes, it would corrupt the state. First, the effect of issuing the dynamic commands during the life of the cluster have been lost, and that was most likely the correct state for the resource. Second, if each of the sharing systems maintain an internal representation of the state of these resources, you now have a situation where the internal representation of the state, for the system most recently accessing the resources, is now inconsistent with the other sharing systems. This paper discusses a method that may be used with clustered systems that share such resources, such that initializing systems do not corrupt current state information, and the internal representation of the state of these resources is consistent amongst all of the members of the cluster.

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Method and Apparatus For Setting The Initial State Of A Resource

When a system joins an existing cluster (i.e. it is not the first system in the cluster), it should not set the state of shared resources to that of a predetermined value. It should instead determine what the current state of the resources are, and update its internal representation to that. An exemplary embodiment of this follows: During system initialization (100), the system joins the cluster (105). As a result of joining the cluster, the system is told if it is the initial system in the cluster, or if it is joining an already active cluster. If the system is told that it is the first system in the cluster (110), then it uses the predefined configuration information to set the initial state of the resources to that which was predetermined by the system administrator (115). If the system is told that it is joining an already active cluster, then it does not set the initial state of the resources and instead communicates with one of the systems in the cluster to find out what the current state of the resources are, and then updates its internal representation of the state so that all members of the cluster have an identical understanding of the state of those resources (120). Upon either processing the predetermined configuration information (115), or synchronizing with an existing member of the cluster (120), system initialization continues (125).

100Enter from system initialization

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