Red Hat GNBD WITH GLOBAL FILE SYSTEM IN RHEL 4.5 Guia de Instalação descarregar pdf (Página 30)

Chapter 4. The DM-Multipath Configuration File

Attribute Description

A value of 0 or immediate specifies that as soon as there is a

path group with a higher priority than the current path group the

system switches to that path group.

A numeric value greater than zero specifies deferred failback,

expressed in seconds.

A value of manual specifies that failback can happen only with

operator intervention.

rr_weight If set to priorities, then instead of sending rr_min_io

requests to a path before calling selector to choose the

next path, the number of requests to send is determined by

rr_min_io times the path's priority, as determined by the

prio_callout program. Currently, there are priority callouts only

for devices that use the group_by_prio path grouping policy,

which means that all the paths in a path group will always have the

same priority.

If set to uniform, all path weights are equal.

no_path_retry A numeric value for this attribute specifies the number of times

the system should attempt to use a failed path before disabling

queueing.

A value of fail indicates immediate failure, without queueing.

A value of queue indicates that queuing should not stop until the

path is fixed.

flush_on_last_del (Red Hat Enterprise Linux 5.3 and later) If set to yes, the

multipathd daemon will disable queueing when the last path to

a device has been deleted.

rr_min_io Specifies the number of I/O requests to route to a path before

switching to the next path in the current path group.

mode (Red Hat Enterprise Linux 5.3 and later) The mode to use for the

multipath device nodes, in octal. The default value is determined

by the process.

uid (Red Hat Enterprise Linux 5.3 and later) The user ID to use for the

multipath device nodes. You must use the numeric user ID. The

default value is determined by the process.

gid (Red Hat Enterprise Linux 5.3 and later) The group ID to use for

the multipath device nodes. You must use the numeric group ID.

The default value is determined by the process.

The following example shows multipath attributes specified in the configuration file for two specific

multipath devices. The first device has a WWID of 3600508b4000156d70001200000b0000 and a

symbolic name of yellow.

The second multipath device in the example has a WWID of 1DEC_____321816758474 and a

symbolic name of red. In this example, the rr_weight attributes is set to priorities.

multipaths {

multipath {

wwid 3600508b4000156d70001200000b0000

alias yellow

path_grouping_policy multibus

path_selector "round-robin 0"

failback manual

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