multipathd ignores dev_loss_tmo and fast_io_fail_tmo settings

Bug #1099875 reported by Tore Anderson
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
multipath-tools (Ubuntu)
New
High
Unassigned

Bug Description

My device section of /etc/multipath.conf contains the following (I'll attach the complete file in a bit):

fast_io_fail_tmo 3
dev_loss_tmo 2147483647

This is also visible in the output from multipathd -k"show config", so it's being correctly parsed. However, the settings appears to be completely ignored by multipathd, as the corresponding sysfs settings doesn't get updated:

$ grep . /sys/class/fc_remote_ports/rport-*/*tmo
/sys/class/fc_remote_ports/rport-2:0-0/dev_loss_tmo:30
/sys/class/fc_remote_ports/rport-2:0-0/fast_io_fail_tmo:off
/sys/class/fc_remote_ports/rport-3:0-0/dev_loss_tmo:30
/sys/class/fc_remote_ports/rport-3:0-0/fast_io_fail_tmo:off

These are the kernel's defaults. I can easily set them manually:

$ echo 3 | tee /sys/class/fc_remote_ports/rport-*/fast_io_fail_tmo
3
$ echo 2147483647 | tee /sys/class/fc_remote_ports/rport-*/dev_loss_tmo
2147483647
$ grep . /sys/class/fc_remote_ports/rport-*/*tmo
/sys/class/fc_remote_ports/rport-2:0-0/dev_loss_tmo:2147483647
/sys/class/fc_remote_ports/rport-2:0-0/fast_io_fail_tmo:3
/sys/class/fc_remote_ports/rport-3:0-0/dev_loss_tmo:2147483647
/sys/class/fc_remote_ports/rport-3:0-0/fast_io_fail_tmo:3

However, this won't survive a reboot, and since SAN paths may appear at any time, adding the above to /etc/rc.local is also not a good way to fix it.

I've also attempted to move the settings to the defaults section and the individual path sections. No change in behaviour.

This bug prevents dm-multipath from quickly moving I/O away from a recently failed SAN path, instead stalling all I/O for 30 seconds. This defeats the purpose of using multipathing in the first place, which is to have highly available I/O access so that production can continue uninterrupted even if parts of the SAN fabric fails.

The setting works on RHEL6, btw.

Revision history for this message
Tore Anderson (toreanderson) wrote :
Revision history for this message
Serge Hallyn (serge-hallyn) wrote :

Thanks for reporting this bug.

You say that multipathd -k"show config" shows the changes you want, could you please show the full output of it? In addition to the output of 'multipath -v4' ?

Revision history for this message
Serge Hallyn (serge-hallyn) wrote :

(marking incomplete pending response from bug submitter - please feel free to re-set to New when attaching the information)

Changed in multipath-tools (Ubuntu):
importance: Undecided → High
status: New → Incomplete
Revision history for this message
Tore Anderson (toreanderson) wrote :
Revision history for this message
Tore Anderson (toreanderson) wrote :
Changed in multipath-tools (Ubuntu):
status: Incomplete → New
Revision history for this message
Thermaltaker (dennis-benndorf) wrote :

I have this problem, too. Searching for a solution I found that guys from redhat had the same problem and fixed it:
https://bugzilla.redhat.com/show_bug.cgi?id=651389

This problem affects all out lucid and precise servers and is really anoying. Cant you port the redhat patch to Ubuntu?

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