[DRBD-user] same(?) drbd/xen kernel panic problem

Tom Brown wc-linbit.com at vmail.baremetal.com
Mon May 11 18:33:33 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Mon, 11 May 2009, Ivars Strazdi wrote:

> Hi DRBD users,
> it looks like I am experiencing similar problem that other people have
> had. In a two node XEN cluster if the first node goes away, the second
> node panics with skb_copy_bits up in stack trace.
> Cluster nodes run stock Debian Lenny (2.6.26-2-xen-686) and DRBD 8.3.1.
> But I am absolutely positive have already disabled protocol offload
> options (ie rx,tx,sg) on both nodes... before DRBD starts (that is, in
> /etc/network/interfaces with post-up option)
> Did I miss anything? What else could I look for?
> Or should I wait for DRBD 8.3.2 which allegedly fixes this problem?

Please either actually read the messages you are attempting to summarize 
(or which somone else mis-summarized).

8.3.2 will not "fix" the problem. It will provide a parameter for turning 
off sendpage support, which is a work-around. basically it provides a 
clean module interface for the 1 line code change that Lars just posted.

[I just want folks to be clear that upgrading from 8.3.1 to 8.3.2 isn't 
going to make the problem go away... but it will give you a way to make a 
change which DOES make the problem go away.]

I had no luck with changing the scatter/gather and checksum parameters, 
for me it was code-change or protocol A.

And replicating the problem is simple enough if you have some test 
machines you can work with... just ifdown the interface on the secondary, 
type sync in the xen guest (domU) and wait about 30 seconds.


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