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From: Miles Fidelman on 14 May 2010 21:00
Hi,

I've just come across an interesting problem that highlights an
interesting not-quite-but.

The short form (the longer form follow below):

- just installed xen (for virtualization) and DRBD (for disk replication
in support of high availability) -- xen virtual machines run "on top of"
DRBD-backed block devices

- the Debian packaged versions of xen and DRBD install init routines in
/etc/init.d and /etc/rc<n>.d - BUT... they name/number the Snn files
such that xen VMs load before DRBD initializes -- i.e., the virtual
machines can't find their disks and fail to come up

I fixed the problem simply by changing the order of initialization,
but... this leads to an interesting question: How, and to whom to I
report this as a bug? It's not a problem with one package, but a
problem with interactions between two packages, and it's not clear if
it's a problem with Debian packaging or with the upstream packages.

Miles Fidelman


-------- Original Message --------

Hi,

I've been building up a new HA system, running Xen on DRBD devices.

Configuration this applies to:
Debian Lenny
xen-linux-system-2.6.26-2-xen-686 package

|**|drbd8-modules-2.6.26-2-686
drbd8-modules-2.6.26-2-xen-686


As I've been building the system, I ran into an interesting problem,
with two symptoms:

1. running VMs would come back up after a reboot, but would hang on
simple tasks

2. non-running VMs, set up for auto-start at boot, would not come up

Turns out, that after pouring through a lot of log files, it became clear what was happening - as confirmed by a quick look in to /etc/rc2.d (DomO):

server2:/etc/rc2.d# ls
README S16ssh S20xend S70drbd S99rmnologin
S10rsyslog S20exim4 S21xendomains S75heartbeat S99stop bootlogd
S12acpid S20openhpid S23ntp S89cron
S12dbus S20smartmontools S25mdadm S99rc.local

xendomains was trying to bring up VMs, before drbd devices were initialized - leading to all kinds of weirdness. The domains would try to come up, get through the boot stages, and then hang as soon as they tried to mount root and swap.

Changing S21xendomains to S76xendomains (after both drbd and hearbeat) solved the problem.

WHICH LEADS TO A QUESTION:

This isn't really a bug with any one piece of code - it's a bug in the interaction, specifically in the naming/ordering of the init package. And I expect that this may be specific to packaging (I'm going to do more digging). SO WHERE DO I FILE A BUG REPORT?

Miles Fidelman



--
In theory, there is no difference between theory and practice.
In<fnord> practice, there is. .... Yogi Berra




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