Multipath Device Attributes; Multipath Devices In Logical Volumes - Red Hat DEVICE-MAPPER MULTIPATH 4.6 Configuration And Administration Manual

Chapter 2. Multipath Devices
multipath device. This should not cause any difficulties if you use LVM to create logical devices
from the multipath device, but if you require that your multipath device names be consistent in
every node in the cluster you perform one of the following procedures:
• Use the option in the
alias
name of the multipath device. The
nodes in a cluster. For information on the
file, see see Section 4, "Multipaths Device Configuration
• If you want the system-defined user-friendly names to be consistent across all nodes in the
cluster, set up all of the multipath devices on one machine. Then copy the
that machine to all the other machines in the cluster. The bindings file is located at
/var/lib/multipath/bindings
with the
bindings_file

3. Multipath Device Attributes

In addition to the
user_friendly_names
attributes. You can modify these attributes for a specific multipath device by creating an entry
for that device in the
multipaths
the section of the multipath configuration file, see see
multipaths
Configuration Attributes".

4. Multipath Devices in Logical Volumes

After creating multipath devices, you can use the multipath device names just as you would use
a physical device name when creating an LVM physical volume. For example, if
/dev/mapper/mpath0
/dev/mapper/mpath0
pvcreate /dev/mapper/mpath0
You can use the resulting LVM physical device when you create an LVM volume group just as
you would use any other LVM physical device.
When you create an LVM logical volume that uses active/passive multipath arrays as the
underlying physical devices, you should include filters in the
that underlie the multipath devices. This is because if the array automatically changes the active
path to the passive path when it receives I/O, multipath will failover and failback whenever LVM
scans the passive path if these devices are not filtered. For active/passive arrays that require a
command to make the passive path active, LVM prints a warning message when this occurs.
To filter all SCSI devices in the multipath configuration file (
in the section of the file.
devices
8
section of the multipath configuration file to set the
multipaths
for the multipath device is consistent across all the
alias
multipaths
by default, but you can set this value to a different location
parameter of the
defaults
and
section of the multipath configuration file. For information on
is the name of a multipath device, the following command will mark
as a physical volume.
section of the multipath configuration
Attributes".
section of the configuration file.
options, a multipath device has numerous
alias
Section 4, "Multipaths Device
lvm.conf
lvm.conf
file from
bindings
file to exclude the disks
), include the following filter