![]() ![]() A value of queue indicates that queuing should not stop until the path is fixed. For example, if you want to change the policy on the multipath device mpath04 from “queue_if_no_path” to “fail_if_no_path”, execute the following: dmsetup message mpath04 0 "fail_if_no_path"Ī numeric value for this attribute specifies the number of times the system should attempt to use a failed pathĪ value of fail indicates immediate failure, without queuing. 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 wich all the paths are unavailable). To avoid this, set the no_path_retry N parameter in the /etc/nf file ( where N is the number of times the system should retry a path). If a multipath device is configured with features “1 queue_if_no_path” then any process that issues I/O will hang until one or more paths are restored. Size=5.0G features=' 1 queue_if_no_path' hwhandler='0' wp=rw ![]() Size=100G features=' 1 queue_if_no_path' hwhandler='0' wp=rw Size=200G features=' 1 queue_if_no_path' hwhandler='0' wp=rw It’s because the feature: queue_if_no_path: multipath -ll | egrep -i "mpath|feature" I managed to find out the root cause for I/O hang after a little more digging. This time, a fiber channel module on storage broke down, which essentially is equivalent to pulling off connections between SAN switch and storage. Once all holders of the device have been removed, the multipath device should be flushed with " multipath -f".The other day this issue reoccurred, but was triggered by another event. #Map in use multipath fullSee dmsetup man page for full explanation of these commands.
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