------- Comment From thorsten.di...@de.ibm.com 2016-02-29 06:27 EDT-------
(In reply to comment #16)
> > Could you attempt to use the Debian package from Sid on top of the Ubuntu
> system?  This will help rule out kernel related issues vs. userspace package
> bugs.
>
> You can download from here
>
> http://ftp.us.debian.org/debian/pool/main/m/multipath-tools/multipath-
> tools_0.5.0+git1.656f8865-4_s390x.deb
>
> And then force install with
>
> sudo dpkg --force all --install
> multipath-tools_0.5.0+git1.656f8865-4_s390x.deb
>
> If this is successful, then I can prepare a package with some updated fixes
> from upstream; there are a number of changes to path related discovery in
> upstream multipath that aren't yet included in the Ubuntu version.

Hi Ryan,

I followed your proposal, installed 
multipath-tools_0.5.0+git1.656f8865-4_s390x.deb as described, and it worked 
fine and as expected, i.e. described problem does not occur.
On another system I installed both 
multipath-tools_0.5.0+git1.656f8865-4_s390x.deb and 
kpartx_0.5.0+git1.656f8865-4_s390x.deb - with the same result.
I did a detach/attach of the zfcp device and found, that it apperas for some 
seconds in status active faulty running, then it changed to failed faulty 
running and remained in that state until reattachment of the device. Then it 
changed back to active ready running.

Hi Christian,

in addition I did the following tests:

1. On a freshly installed xenial (installer version 427, kernel 4.4.0-8) with 
the already mentioned multipath.conf I found, that no zfcphbaapi stuff is 
installed per default.
kernel 4.4.0-8
multipath-tools 0.5.0-7ubuntu15 (was 7ubuntu14 before) and kpartx 
0.5.0-7ubuntu15
I did a detach/attach of the zfcp device and found, that it apperas for some 
seconds in status active faulty offline, then it changed to failed faulty 
offline and vanished and did not reappear upon reattachment of the device. I 
had the zfcp LUNs configure manually (via sysfs)

2. Then I installed zfcp-hbaapi-utils_2.1.1-0ubuntu1_s390x.deb and
libzfcphbaapi0_2.1.1-0ubuntu1_s390x.deb on top. With these two
additional packages I could not reproduce this problem.

3. I installed a system with kernel 4.4.0-7 and multipath-tools
0.5.0-7ubuntu14 + the above mentioned zfcphbaapi stuff. Problem was
reproducable.

4. I updated that system to multipath-tools 0.5.0-7ubuntu15. Problem was
still reproducable.

5. I updated that system to kernel 4.4.0-8. It should be now similar to
case #2. But problem was still reproducable. strange.

6. I switched several times back and forth between multipath-tools
0.5.0-7ubuntu15 and multipath-tools_0.5.0+git1.656f8865-4_s390x.deb.
With git1 it worked always, with 7ubuntu15 never. (although it did on a
freshly installed system, see #2)

So, for now we have two ways to solve/circumvent this problem:
a) use an updated multipath-tools package (from debian sid)
b) use an updated multipath-tools/kpartx packages from ubuntu (>= version 
0.5.0-7ubuntu15) AND zfcp-hbaapi-utils_2.1.1-0ubuntu1_s390x.deb and 
libzfcphbaapi0_2.1.1-0ubuntu1_s390x.deb on top. But that didn't help always 
(see case #5 above)

I found different values for path_selector in multipath-tools versions of 
ubuntu and debian:
ubuntu15: round-robin 0
debian-git: service-time 0
Then I set this in multipath.conf to the (usual) default "round-robin 0"
And with debian-git version the problem was still solved. So this setting 
should not matter.

Ryan,
although obviously only fixes from multipath-tools_0.5.0+git1.656f8865-4 are 
required to fix this problem, please consider and analyze, if it is better to 
get the complete set of patches in both multipath-tools AND kpartx from debian 
upstream (sid) instead of cherry picking some fixes.
The debian sid combination of multipath-tools AND kpartx does obviously not 
harm and is already 6 weeks old.

Anyway, I will do some other test with this combination.

-- 
You received this bug notification because you are a member of Ubuntu
Server Team, which is subscribed to multipath-tools in Ubuntu.
https://bugs.launchpad.net/bugs/1540407

Title:
  multipathd drops paths of a temporarily lost device

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/multipath-tools/+bug/1540407/+subscriptions

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