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

Ivars Strazdiņš ivars.strazdins at gmail.com
Mon May 11 18:53:21 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.


Tom Brown wrote:
> 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.
>   
Tom,
thanks for clarification. AFAIK protocol A cannot be used with 
"allow-two-primaries" option, I have to sacrifice live migration.
Perhaps I am missing something [again] but I haven't seen in DRBD 
mailing list that 1 line code change you mentioned.

Regards,
Ivars



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