[dm-devel] Question regarding failback option in multipath.conf

[Eli Klein]

I'm running into an issue where the failback option in multipath.conf  
is being ignored.  I've tried to set this to a value > 0 to cause dm  
to pause before reinstating a recovered path, but it reinstates the  
path immediately.  The same is true when setting the value to  
"manual", the path is reinstated immediately.  The delay is most  
useful when a ethernet switch has failed or rebooted.  During the boot  
of the switch, the interface comes up and drops again multiple times.   
I'd love to be able to introduce a delay before DM marks the path as  
reinstated after a recovery.  This would save me the hassle of running  
into I/O errors (and occasional filesystem RO) as the path bounces  
while the switch is booting.

Thanks in advance for any help or suggestions!

-Eli

I've included my multipath.conf as well as output from multipath -ll  
below:

multipath.conf:

blacklist {
         devnode "sda$"
#        devnode "*"
}

## By default, devices with vendor = "IBM" and product = "S/390.*" are
## blacklisted. To enable mulitpathing on these devies, uncomment the
## following lines.
#blacklist_exceptions {
#	device {
#		vendor	"IBM"
#		product	"S/390.*"
#	}
#}

## Use user friendly names, instead of using WWIDs as names.
defaults {
	user_friendly_names yes
}
##
## Here is an example of how to configure some standard options.
##
#
defaults {
	udev_dir		/dev
	polling_interval 	10
	selector		"round-robin 0"
	path_grouping_policy	multibus
	getuid_callout		"/sbin/scsi_id -g -u -s /block/%n"
	prio_callout		/bin/true
	path_checker		readsector0
	rr_min_io		10
	rr_weight		priorities
	failback		120
	features		"1 queue_if_no_path"
	no_path_retry		1
	user_friendly_name	yes
}

multipath -ll:

mpath2 (36000eb3945b8703a00000000000000f4) dm-3 LEFTHAND,iSCSIDisk
[size=400G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
  \_ 192:0:0:0 sdl 8:176 [active][ready]
  \_ 191:0:0:0 sdf 8:80  [active][ready]
mpath152 (36000eb3945b8703a0000000000001431) dm-2 LEFTHAND,iSCSIDisk
[size=300G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
  \_ 186:0:0:0 sdh 8:112 [active][ready]
  \_ 185:0:0:0 sde 8:64  [active][ready]
mpath149 (36000eb3945b8703a0000000000001429) dm-5 LEFTHAND,iSCSIDisk
[size=300G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
  \_ 189:0:0:0 sdc 8:32  [active][ready]
  \_ 190:0:0:0 sdi 8:128 [active][ready]
mpath151 (36000eb3945b8703a000000000000142d) dm-6 LEFTHAND,iSCSIDisk
[size=300G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
  \_ 188:0:0:0 sdj 8:144 [active][ready]
  \_ 187:0:0:0 sdg 8:96  [active][ready]
mpath150 (36000eb3945b8703a0000000000001435) dm-4 LEFTHAND,iSCSIDisk
[size=200G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
  \_ 184:0:0:0 sdk 8:160 [active][ready]
  \_ 183:0:0:0 sdd 8:48  [active][ready]
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