Bug#716655: multipath-tools: mention aliases in README.debian

[Ritesh Raj Sarraf]

On Thursday 11 July 2013 05:40 PM, Vincent McIntyre wrote:
> I know the mappings file is supposed to prevent this but we have
> seen this mechanism go nuts at various times on lenny & squeeze.
> I don't have any clear evidence (or you would know about it)
> but my suspicion is that on some boots the device enumeration order
> changes for some reason and Something Funky (TM) happens at the
> coalescence stage.
> This may have gone away now. Maybe it was locking.
> It may have been us just doing an ill-considered multipath -F
> (or _not_ doing one) but it's happened enough that seems unlikely
> for that to be the explanation.
> It mostly happens when new devices are attached or removed from a host
> (FC switch change while host is shut down).
>
> Do you have any advice on how to provide useful information if we
> see this again?
> We are currently running squeeze but will migrate to wheezy soonish.
> We always run multipathd with -v 3 but have never managed to get
> anything useful in syslog - it seems to happen before syslog is started.
> We always have separate / and /var partitions, /boot is part of /.
> We never boot off multipath.

From what you are explaining, it looks to be the case of the locking
issue. This issue was commonly seen during boot times or device
discovery / driver reloads.

The issue was hard to reproduce. But, in general, if you run into
multipath issues in the future, you would want to increase the verbosity
level in your multipathd daemon. We added a verbosity feature into the
daemon for this purpose only. With the verbosity combination of mulipath
and multipathd, you can be in a better position to gather logs when a
bug is hit.

For issues that occur before syslog, you'll have to rely on netconsole.

As Storage solution vendor, we've recommended our customers to move away
from user_friendly_names long ago.

-- 
Ritesh Raj Sarraf
RESEARCHUT - http://www.researchut.com
"Necessity is the mother of invention."


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