Planning For Multipathing; Guidelines For Multipathing - Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010 Administration Manual

Typical connection problems involve faulty adapters, cables, or controllers. When you configure
multipath I/O for a device, the multipath driver monitors the active connection between devices.
When the multipath driver detects I/O errors for an active path, it fails over the traffic to the device's
designated secondary path. When the preferred path becomes healthy again, control can be returned
to the preferred path.

7.2 Planning for Multipathing

Section 7.2.1, "Guidelines for Multipathing," on page 44
Section 7.2.2, "Using Multipathed Devices," on page 45
Section 7.2.3, "Using LVM2 on Multipath Devices," on page 46
Section 7.2.4, "Using mdadm with Multipath Devices," on page 46
Section 7.2.5, "Using --noflush with Multipath Devices," on page 46
Section 7.2.6, "Partitioning Multipath Devices," on page 47
Section 7.2.7, "Supported Architectures for Multipath I/O," on page 47
Section 7.2.8, "Supported Storage Arrays for Multipathing," on page 47

7.2.1 Guidelines for Multipathing

Use the guidelines in this section when planning your multipath I/O solution.
"Prerequisites" on page 44
"Vendor-Provided Multipath Solutions" on page 44
"Disk Management Tasks" on page 45
"Software RAIDs" on page 45
"High-Availability Solutions" on page 45
"Volume Managers" on page 45
"Virtualization Environments" on page 45
Prerequisites
Multipathing is managed at the device level.
The storage array you use for the multipathed device must support multipathing. For more
information, see
You need to configure multipathing only if multiple physical paths exist between host bus
adapters in the server and host bus controllers for the block storage device. You configure
multipath for the logical device as seen by the server.
Vendor-Provided Multipath Solutions
For some storage arrays, the vendor provides its own multipathing software to manage multipathing
for the array's physical and logical devices. In this case, you should follow the vendor's instructions
for configuring multipathing for those devices.
44 SLES 11: Storage Administration Guide
Section 7.2.8, "Supported Storage Arrays for Multipathing," on page 47.