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[dm-devel] Multipath only round-robin



Hello together,

I set up a testenviroment with 2xQLA2342 and have a active-active
capable Disk. I see the LUN 4 times which is fine and multipathed it
successfully to one. Failover works fine but writing is a bit "fuzzy"
since he only uses one path for 3sec or so and then the other path for
3 seconds - so a clearly "round-robin" bevaviour. As you can see in my
multipath.conf it should use multibus - so why is he doing this? I
think i saw an option in the multipath.conf but i don´t know which
value is "sensefull"...
Also i´am not sure why multipath says [undef] ?

Here some details:

linux-m8u1:/mnt # multipath -l
myisecondmultipath (36000d7700000030644cb1a8097fc3936) FALCON,IPSTOR DISK
[size=19G][features=1 queue_if_no_path][hwhandler=0]
\_ round-robin 0 [prio=0][active]
\_ 2:0:0:1 sdc 8:32  [active][undef]
\_ 2:0:1:1 sde 8:64  [active][undef]
\_ 3:0:0:1 sdg 8:96  [active][undef]
\_ 3:0:1:1 sdi 8:128 [active][undef]
myfirstmultipath (36000d77e00001e9a50d21a80a0506232) FALCON,IPSTOR DISK
[size=2G][features=1 queue_if_no_path][hwhandler=0]
\_ round-robin 0 [prio=0][active]
\_ 2:0:0:0 sdb 8:16  [active][undef]
\_ 2:0:1:0 sdd 8:48  [active][undef]
\_ 3:0:0:0 sdf 8:80  [active][undef]
\_ 3:0:1:0 sdh 8:112 [active][undef]

why does he say [undef] ???

Here the multipath.conf:

defaults {
       multipath_tool  "/sbin/multipath"
       # udev_dir      /dev
       # polling_interval 10
       # Pfadprüfinterval
       polling_interval 5

       # Queue IO for 36*5=180 Seconds=3min
(retries*polling_interval) then fail IO
       # 3 min=default dynapath timeout
       no_path_retry 36

       # default_selector round-robin
       # default_selector_args 0

       default_path_grouping_policy    multibus
       # default_getuid_callout        "/sbin/scsi_id -g -u -s /block/%n"
       #default_prio_callout    "/etc/multipath_get_prio %n"
       #default_prio_callout    "/bin/false"
}

#
# name    : multipaths
# scope   : multipath & multipathd
# desc    : list of multipaths finest-grained settings

multipaths {
       multipath {
               wwid                    36000d77e00001e9a50d21a80a0506232
               alias                   myfirstmultipath
       }
       multipath {
               wwid                    36000d7700000030644cb1a8097fc3936
               alias                   myisecondmultipath
       }
}

uname -a
Linux linux-m8u1 2.6.16.21-0.8-smp #1 SMP Mon Jul 3 18:25:39 UTC 2006
i686 i686 i386 GNU/Linux

Hopefully someone could shine some light on that...

Thanks in advance
Markus


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