Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010, Administration Manual, Page: 43 / 140

Managing Multipath I/O for Devices
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Managing Multipath I/O for
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This section describes how to manage failover and path load balancing for multiple paths between
the servers and block storage devices.
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Section 7.1, “Understanding Multipathing,” on page 43
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Section 7.2, “Planning for Multipathing,” on page 44
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Section 7.3, “Multipath Management Tools,” on page 50
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Section 7.4, “Configuring the System for Multipathing,” on page 54
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Section 7.5, “Enabling and Starting Multipath I/O Services,” on page 60
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Section 7.6, “Configuring Path Failover Policies and Priorities,” on page 61
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Section 7.7, “Tuning the Failover for Specific Host Bus Adapters,” on page 69
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Section 7.8, “Configuring Multipath I/O for the Root Device,” on page 69
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Section 7.9, “Configuring Multipath I/O for an Existing Software RAID,” on page 70
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Section 7.10, “Scanning for New Devices without Rebooting,” on page 71
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Section 7.11, “Scanning for New Partitioned Devices without Rebooting,” on page 73
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Section 7.12, “Viewing Multipath I/O Status,” on page 74
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Section 7.13, “Managing I/O in Error Situations,” on page 75
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Section 7.14, “Resolving Stalled I/O,” on page 76
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Section 7.15, “Additional Information,” on page 76
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Section 7.16, “What’s Next,” on page 77
7.1 Understanding Multipathing
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Section 7.1.1, “What Is Multipathing?,” on page 43
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Section 7.1.2, “Benefits of Multipathing,” on page 43
7.1.1 What Is Multipathing?
Multipathing is the ability of a server to communicate with the same physical or logical block
storage device across multiple physical paths between the host bus adapters in the server and the
storage controllers for the device, typically in Fibre Channel (FC) or iSCSI SAN environments. You
can also achieve multiple connections with direct attached storage when multiple channels are
available.
7.1.2 Benefits of Multipathing
Linux multipathing provides connection fault tolerance and can provide load balancing across the
active connections. When multipathing is configured and running, it automatically isolates and
identifies device connection failures, and reroutes I/O to alternate connections.