Novell LINUX ENTERPRISE SERVER 10 SP3 - ARCHITECTURE-SPECIFIC, Administration Manual

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54 SLES 10 SP3: Storage Administration Guide
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Section 5.4.3, “Configuring the Server for Multipathing,” on page 55
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Section 5.4.4, “Adding multipathd to the Boot Sequence,” on page 55
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Section 5.4.5, “Creating and Configuring the /etc/multipath.conf File,” on page 56
5.4.1 Preparing SAN Devices for Multipathing
Before configuring multipath I/O for your SAN devices, prepare the SAN devices, as necessary, by
doing the following:
Š Configure and zone the SAN with the vendor’s tools.
Š
Configure permissions for host LUNs on the storage arrays with the vendor’s tools.
Š Install the Linux HBA driver module. Upon module installation, the driver automatically scans
the HBA to discover any SAN devices that have permissions for the host. It presents them to
the host for further configuration.
NOTE: Ensure that the HBA driver you are using does not have native multipathing enabled.
See the vendor’s specific instructions for more details.
Š
After the driver module is loaded, discover the device nodes assigned to specific array LUNs or
partitions.
If the LUNs are not seen by the HBA driver,
lsscsi
can be used to check whether the SCSI devices
are seen correctly by the operating system. When the LUNs are not seen by the HBA driver, check
the zoning setup of the SAN. In particular, check whether LUN masking is active and whether the
LUNs are correctly assigned to the server.
If the LUNs are seen by the HBA driver, but there are no corresponding block devices, additional
kernel parameters are needed to change the SCSI device scanning behavior, such as to indicate that
LUNs are not numbered consecutively. For information, see
Options for SCSI Device Scanning
(http://support.novell.com/techcenter/sdb/en/2005/06/drahn_scsi_scanning.html) in the Novell
Support Knowledgebase.
5.4.2 Partitioning Multipathed Devices
Partitioning devices that have multiple paths is not recommended, but it is supported.
SUSE Linux Enterprise Server 10
In SUSE Linux Enterprise Server 10, you can use the
kpartx
tool to create partitions on
multipathed devices without rebooting. You can also partition the device before you attempt to
configure multipathing by using the Partitioner function in YaST2 or by using a third-party
partitioning tool.
SUSE Linux Enterprise Server 9
In SUSE Linux Enterprise Server 9, if you want to partition the device, you should configure its
partitions before you attempt to configure multipathing by using the Partitioner function in YaST2 or
by using a third-party partitioning tool. This is necessary because partitioning an existing
multipathed device is not supported. Partitioning operations on multipathed devices fail if
attempted.