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Disk Management Tasks
Perform the following disk management tasks before you attempt to configure multipathing for a
physical or logical device that has multiple paths:
Use third-party tools to carve physical disks into smaller logical disks.
Use third-party tools to partition physical or logical disks. If you change the partitioning in the
running system, the Device Mapper Multipath (DM-MP) module does not automatically detect
and reflect these changes. DM-MP must be reinitialized, which usually requires a reboot.
Use third-party SAN array management tools to create and configure hardware RAID devices.
Use third-party SAN array management tools to create logical devices such as LUNs. Logical
device types that are supported for a given array depend on the array vendor.
Software RAIDs
The Linux software RAID management software runs on top of multipathing. For each device that
has multiple I/O paths and that you plan to use in a software RAID, you must configure the device
for multipathing before you attempt to create the software RAID device. Automatic discovery of
multipathed devices is not available. The software RAID is not aware of the multipathing
management running underneath.
High-Availability Solutions
High-availability solutions for clustering typically run on top of the multipathing server. For
example, the Distributed Replicated Block Device (DRBD) high-availability solution for mirroring
devices across a LAN runs on top of multipathing. For each device that has multiple I/O paths and
that you plan to use in a DRDB solution, you must configure the device for multipathing before you
configure DRBD.
Volume Managers
Volume managers such as LVM2 and EVMS run on top of multipathing. You must configure
multipathing for a device before you use LVM2 or EVMS to create segment managers and file
systems on it.
Virtualization Environments
When using multipathing in a virtualization environment, the multipathing is controlled in the host
server environment. Configure multipathing for the device before you assign it to a virtual guest
machine.
5.2.2 Using Multipathed Devices Directly or in EVMS
If you want to use the entire LUN directly (for example, if you are using the SAN features to
partition your storage), you can simply use the
, your application, etc.
fstab
If the user-friendly names option is enabled in the
use the
/dev/mapper/mpathn
information, see
"Configuring User-Friendly Names or Alias Names in /etc/multipath.conf" on
page
57.
/dev/disk/by-id/xxx
/etc/multipath.conf
device name because this name is aliased to the devices ID. For
names directly for
mkfs
file, you can optionally
Managing Multipath I/O for Devices
,
45
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Troubleshooting
