Q: multipathd: queue_if_no_path
Hi,
this is a bit off-topic, but esential: After experiencing a network failure for
about four minutes, I was watching the syslog (the system had no problems so
far):
Mar 30 15:24:33 testhost multipathd: sdc: tur checker reports path is up
Mar 30 15:24:33 testhost multipathd: 8:32: reinstated
Mar 30 15:24:33 testhost multipathd: L112_09: queue_if_no_path enabled
Mar 30 15:24:33 testhost multipathd: L112_09: Recovered to normal mode
Mar 30 15:24:33 testhost multipathd: L112_09: remaining active paths: 1
Mar 30 15:24:33 testhost multipathd: L112_09: switch to path group #2
Mar 30 15:24:33 testhost multipathd: L112_09: switch to path group #2
I'm surprised: I thought queue_if_no_path would be enabled if the device
fails,
not if the device recovered!
The multipath configuration for the device looks like this:
device {
vendor HP
product HSV2.*
path_grouping_policy group_by_prio
path_checker tur
prio_callout mpath_prio_alua /dev/%n
failback immediate
#polling_interval 30
no_path_retry 1000
features 1 queue_if_no_path
}
Does anbody have similar experience?
Regards,
Ulrich
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Re: Q: multipathd: queue_if_no_path
On Wed, Apr 01, 2009 at 01:05:30PM +0200, Ulrich Windl wrote: Hi, this is a bit off-topic, but esential: After experiencing a network failure for about four minutes, I was watching the syslog (the system had no problems so far): Mar 30 15:24:33 testhost multipathd: sdc: tur checker reports path is up Mar 30 15:24:33 testhost multipathd: 8:32: reinstated Mar 30 15:24:33 testhost multipathd: L112_09: queue_if_no_path enabled Mar 30 15:24:33 testhost multipathd: L112_09: Recovered to normal mode Mar 30 15:24:33 testhost multipathd: L112_09: remaining active paths: 1 Mar 30 15:24:33 testhost multipathd: L112_09: switch to path group #2 Mar 30 15:24:33 testhost multipathd: L112_09: switch to path group #2 I'm surprised: I thought queue_if_no_path would be enabled if the device fails, not if the device recovered! It should be enabled all the time - I think you are seeing the code path that figures out that queue_if_nopath is set and it prints an informational message about it (the queue of I/O only happens when access to the disk is offline) --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups open-iscsi group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/open-iscsi -~--~~~~--~~--~--~---
Re: Q: multipathd: queue_if_no_path
Ulrich Windl wrote:
Hi,
this is a bit off-topic, but esential: After experiencing a network failure
for
about four minutes, I was watching the syslog (the system had no problems so
far):
Mar 30 15:24:33 testhost multipathd: sdc: tur checker reports path is up
Mar 30 15:24:33 testhost multipathd: 8:32: reinstated
Mar 30 15:24:33 testhost multipathd: L112_09: queue_if_no_path enabled
Mar 30 15:24:33 testhost multipathd: L112_09: Recovered to normal mode
Mar 30 15:24:33 testhost multipathd: L112_09: remaining active paths: 1
Mar 30 15:24:33 testhost multipathd: L112_09: switch to path group #2
Mar 30 15:24:33 testhost multipathd: L112_09: switch to path group #2
I'm surprised: I thought queue_if_no_path would be enabled if the device
fails,
not if the device recovered!
I think it might be a bad log message.
The multipath configuration for the device looks like this:
device {
vendor HP
product HSV2.*
path_grouping_policy group_by_prio
path_checker tur
prio_callout mpath_prio_alua /dev/%n
failback immediate
#polling_interval 30
no_path_retry 1000
features 1 queue_if_no_path
}
I think you might have conflicting values here. The no_path_retry value
of 1000 would put a upper limit on how long it queues io. Eventually
fail the IO after the 1000 timeout value. But I think queue_if_no_path
means to queue until the problem is resolved or dm is stopped. You might
want to ask dm-devel or see the docs. I am not 100% sure. I normally use
one or the other.
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