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5.4. Issues with queue_if_no_path feature
If
features "1 queue_if_no_path"
is specified in the /etc/multipath.conf
file, then any process that issues I/O will hang until one or more paths are restored. To avoid this, set the no_path_retry
N
parameter in the /etc/multipath.conf
file (where N
is the number of times the system should retry a path).
When you set the
no_path_retry
parameter, remove the features "1 queue_if_no_path"
option from the /etc/multipath.conf
file as well. If, however, you are using a multipathed device for which the features "1 queue_if_no_path"
option is set as a compiled-in default, as it is for many SAN devices, you must explicitly add features "0"
to override this default. You can do this by copying the existing devices section for your device from /usr/share/doc/device-mapper-multipath-0.4.7/multipath.conf.defaults
into /etc/multipath.conf
and editing it to suit your needs.
If you need to use the
features "1 queue_if_no_path"
option and you experience the issue noted here, use the dmsetup
command to edit the policy at runtime for a particular LUN (that is, for which all the paths are unavailable). For example, if you want to change the policy on the multipath device mpath2
from "queue_if_no_path"
to "fail_if_no_path"
, execute the following command.
dmsetup message mpath2 0 "fail_if_no_path"
Note that you must specify the
mpath
n
alias rather than the path.