# US 7,610,429 B2 · Method and system for determining device criticality in a computer configuration

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- Number: US 7,610,429 B2
- Document ID: US7610429B2
- Status: Granted
- Kind: B2
- Application number: 11/668,493
- Filed: 2007-01-30
- Published: 2008-07-31
- Granted: 2009-10-27
- Earliest claimed: 2007-01-30
- Assignees: Hewlett-Packard Development Company, L.P.
- Inventors: Kishore Kumar Muppirala; Santosh Rao; Harish S. Babu; Ashok Rajagopalan
- Web page: https://patentgrep.com/patent/US7610429B2

## CPC

- G06F 11/2247: {Verification or detection of system hardware configuration}
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A method for determining the criticality of a device in a multi-path computer configuration comprising the steps of: traversing a directed acyclic graph representing a platform hierarchy; and determining paths within the directed acyclic graph affected by the removal of the device. A computer system comprising a directed acyclic graph data structure representing a platform hierarchy; and a control arrangement for traversing the directed acyclic graph to determining paths therein affected by removal of a device.

## Claims

### Claim 1

A method for determining the criticality of a device during a hot-plug operation in a multi-path computer configuration comprising the steps of:
traversing a directed acyclic graph representing a platform hierarchy during the hot-plug operation;
determining paths within the directed acyclic graph affected by the hot-plug operation of the device;
determining devices corresponding to each affected access path;
determining devices that lose all their access paths; and
determining usage in the system of at least the devices that lose all their access paths, wherein the usage of devices in the system is determined from attributes stored at the nodes of the directed acyclic graph and wherein the attributes comprise at least one of whether the device is a boot device, or whether the device is a quorum disk.

### Claim 2 (depends on 1)

A method as claimed in claim 1 comprising generating a device criticality message.

### Claim 3 (depends on 2)

A method as claimed in claim 2 wherein, if the usage of the devices that lose all their access paths impacts user level processes, reporting an application level criticality and/or loss of access to data for user applications.

### Claim 4 (depends on 1)

A method as claimed in claim 1, wherein the directed acyclic graph is maintained by the operating system.

### Claim 5 (depends on 1)

A method for carrying out a hot plug removal operation in a multi-path computer configuration comprising determining the criticality of the device to be removed using a method as claimed in claim 1.

### Claim 6 (depends on 5)

A method as claimed in claim 5 comprising determining that no devices lose all their access paths and permitting the hot-plug operation with a warning to the user that there could be performance degradation.

### Claim 7

A computer system for determining the criticality of a device during a hot-plug operation in a multi-path computer configuration comprising a directed acyclic graph data structure representing a platform hierarchy; and a control arrangement for traversing the directed acyclic graph during the hot-plug operation to determining paths therein affected by the hot-plug operation of the device, wherein the control arrangement determines devices corresponding to each affected access path, determines devices that lose all their access paths, and determines the usage in the system of at least the devices that lose all their access paths, wherein the usage of devices in the system is determined from attributes stored at the nodes of the directed acyclic graph and wherein the attributes comprise at least one of: whether the device is a boot device, or whether the device is a quorum disk.

### Claim 8 (depends on 7)

A computer system as claimed in claim 7 wherein the control arrangement is arranged to generate a device criticality message.

### Claim 9 (depends on 8)

A computer system as claimed in claim 8 wherein, if the usage of the devices that lose all their access paths impacts user level processes, the control arrangement reports an application level criticality and/or loss of access to data for user applications.

### Claim 10 (depends on 7)

A computer system as claimed in claim 7 comprising an operating system for maintaining the directed acyclic graph.

### Claim 11 (depends on 7)

A computer system as claimed in claim 7 comprising an expansion bus having hot plug removal capability in which the control arrangement is operable to determine the criticality of a device to be removed.

### Claim 12 (depends on 7)

A computer system as claimed in claim 7 wherein the computer system is a cluster.