Bug#571617: multipath-tools: multipathd "switch multipath group" leads to strange state

[John Hughes]

Package: multipath-tools
Version: 0.4.8+git0.761c66f-7
Severity: normal


doing repeated "switch multipath group" commands leaves a multipath in
a strange state with both paths "enabled".

   multipathd> show multipath 35000c50012b1450f topology
   35000c50012b1450f dm-25 SEAGATE,ST373455SS
   size=68G features='0' hwhandler='0' wp=rw
   |-+- policy='round-robin 0' prio=1 status=active
   | `- 3:0:24:0 sdy  65:128 active ready running
   `-+- policy='round-robin 0' prio=1 status=enabled
     `- 4:0:24:0 sdbc 67:96  active ready running

Ok, all I/O is going to /dev/sdy, the "active" path.

   multipathd> switch multipath 35000c50012b1450f group 2
   ok

Now I/O is going to  /dev/sdbc, but:

   multipathd> show multipath 35000c50012b1450f topology
   35000c50012b1450f dm-25 SEAGATE,ST373455SS
   size=68G features='0' hwhandler='0' wp=rw
   |-+- policy='round-robin 0' prio=1 status=enabled
   | `- 3:0:24:0 sdy  65:128 active ready running
   `-+- policy='round-robin 0' prio=1 status=enabled
     `- 4:0:24:0 sdbc 67:96  active ready running

Both paths are shown enabled.  Which is active?

multipath gets it right:

   # multipath -l 35000c50012b1450f
   35000c50012b1450f dm-25 SEAGATE,ST373455SS
   size=68G features='0' hwhandler='0' wp=rw
   |-+- policy='round-robin 0' prio=-1 status=enabled
   | `- 3:0:24:0 sdy  65:128 active undef running
   `-+- policy='round-robin 0' prio=-1 status=active
     `- 4:0:24:0 sdbc 67:96  active undef running


-- Package-specific info:
/etc/multipath.conf does not exist.


-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.32-2-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages multipath-tools depends on:
ii  initscripts         2.87dsf-8.1          scripts for initializing and shutt
ii  kpartx              0.4.8+git0.761c66f-7 create device mappings for partiti
ii  libaio1             0.3.107-7            Linux kernel AIO access library - 
ii  libc6               2.10.2-6             Embedded GNU C Library: Shared lib
ii  libdevmapper1.02.1  2:1.02.39-1          The Linux Kernel Device Mapper use
ii  libncurses5         5.7+20090803-2       shared libraries for terminal hand
ii  libreadline6        6.1-1                GNU readline and history libraries
ii  lsb-base            3.2-23               Linux Standard Base 3.2 init scrip
ii  udev                151-2                /dev/ and hotplug management daemo

multipath-tools recommends no packages.

Versions of packages multipath-tools suggests:
pn  multipath-tools-boot          <none>     (no description available)

-- no debconf information