Xen users - Jan 2010 - drbd non-live migration with drbd

Hi,

I''m trying to achieve non-live migration with drbd using
primary/secondary setup (not live primary/primary like everyone else,
I think that the risk of running two domUs on a same drbd resource is
too high)

Is this possible? When I try migrating, the primary drbd device goes
down to secondary mode but the destination device never goes to
primary and as a result i get a locked-up domU.

using centos5 x86_64 and xen 3.4.1 from www.gitco.de/linux but got the
same results with stock xen on centos5 i386



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This is a question for Linbit or DRBD mailing list.
I can however tell you, that for live migration you have to have both 
resources mounted in primary (for at least short period of time).
For PV''s this is possible using drbd OCF ra drbd instead of phy in Xen 
config, but has some catches related to outdating drbd.
For live migration of HVM, you have to have active/active or. 
promoted/promoted.

Regards,
M.

Aleksandar Ivanisevic wrote:
> Hi,
>
> I''m trying to achieve non-live migration with drbd using
> primary/secondary setup (not live primary/primary like everyone else,
> I think that the risk of running two domUs on a same drbd resource is
> too high)
>
> Is this possible? When I try migrating, the primary drbd device goes
> down to secondary mode but the destination device never goes to
> primary and as a result i get a locked-up domU.
>
> using centos5 x86_64 and xen 3.4.1 from www.gitco.de/linux but got the
> same results with stock xen on centos5 i386
>
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>   
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On Mon, Jan 25, 2010 at 10:54 PM, Aleksandar Ivanisevic
<aleksandar@ivanisevic.de> wrote:
> I''m trying to achieve non-live migration with drbd using
> Is this possible? When I try migrating, the primary drbd device goes
> down to secondary mode but the destination device never goes to
> primary and as a result i get a locked-up domU.
You might be able to work around that by using "xm save", transfer the
checkpoint file manually, change drbd primary-secondary, then do "xm
restore".

-- 
Fajar

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Martin Gombač <martin@isg.si> writes:
> This is a question for Linbit or DRBD mailing list.
I don''t think so, since drbd as such works as expected.
> I can however tell you, that for live migration you have to have both
> resources mounted in primary (for at least short period of time).
I don''t want live migration, this is why i wrote non-live in the
subject ;)
> For PV''s this is possible using drbd OCF ra drbd instead of phy in
Xen
> config, but has some catches related to outdating drbd.
Which catches? Where is this documented? I thought all you have to do
is use drbd block scripts and xen will take care of everything.
> For live migration of HVM, you have to have active/active
> or. promoted/promoted.
Yup, that works, I''m just worried of what happens to the disk if
someone starts VMs on both ends.
>
> Regards,
> M.
>
> Aleksandar Ivanisevic wrote:
>> Hi,
>>
>> I''m trying to achieve non-live migration with drbd using
>> primary/secondary setup (not live primary/primary like everyone else,
>> I think that the risk of running two domUs on a same drbd resource is
>> too high)
>>
>> Is this possible? When I try migrating, the primary drbd device goes
>> down to secondary mode but the destination device never goes to
>> primary and as a result i get a locked-up domU.
>>
>> using centos5 x86_64 and xen 3.4.1 from www.gitco.de/linux but got the
>> same results with stock xen on centos5 i386
>>
>>
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@lists.xensource.com
>> http://lists.xensource.com/xen-users
>>   
-- 
Ivanisevicu, pokusaj se za promjenu drzati teme i replicirati na ono o 
cemu sugovornik pise. Osim sto je tvoje pracenje "koji me vrag zapravo 
muci" off-topic na Linux grupi, radi se i o zabadanju njuske u moje 
privatne stvari. Vec si pokazao nedostatak dobrog odgoja no ovo granici 
sa sociopatijom. -- Mladen Gogala, hr.comp.os.linux


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"Fajar A. Nugraha" <fajar@fajar.net> writes:
> On Mon, Jan 25, 2010 at 10:54 PM, Aleksandar Ivanisevic
> <aleksandar@ivanisevic.de> wrote:
>> I''m trying to achieve non-live migration with drbd using
>
>> Is this possible? When I try migrating, the primary drbd device goes
>> down to secondary mode but the destination device never goes to
>> primary and as a result i get a locked-up domU.
>
> You might be able to work around that by using "xm save",
transfer the
> checkpoint file manually, change drbd primary-secondary, then do "xm
> restore".
Thats exactly what I am doing now, I was hoping for an improvement ;)



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On Tue, Jan 26, 2010 at 4:50 PM, Aleksandar Ivanisevic
<aleksandar@ivanisevic.de> wrote:
>> For PV''s this is possible using drbd OCF ra drbd instead of
phy in Xen
>> config, but has some catches related to outdating drbd.
>
> Which catches? Where is this documented? I thought all you have to do
> is use drbd block scripts and xen will take care of everything.
Have you tried this? I''m using drbd (tried 8.2 and 8.3) with Xen
3.4.1, drbd block script simply doesn''t work. I finally settled with
using drbd 8.3 and phy:/dev/drbd/by-res/

-- 
Fajar

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On 01/26/2010 12:28 PM, Fajar A. Nugraha wrote:
> On Tue, Jan 26, 2010 at 4:50 PM, Aleksandar Ivanisevic
> <aleksandar@ivanisevic.de>  wrote:
>>> For PV''s this is possible using drbd OCF ra drbd instead
of phy in Xen
>>> config, but has some catches related to outdating drbd.
>>
>> Which catches? Where is this documented? I thought all you have to do
>> is use drbd block scripts and xen will take care of everything.
>
> Have you tried this? I''m using drbd (tried 8.2 and 8.3) with Xen
> 3.4.1, drbd block script simply doesn''t work. I finally settled
with
> using drbd 8.3 and phy:/dev/drbd/by-res/
it works, sort of, it is all pretty fishy

if you are using pygrub drbd resource heeds to be named the same as the 
device (resource drbd0 for /dev/drbd0, etc..) or you can patch blkif.py 
as in this bug (comment #2)

http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1438

it will work as long as you put drbd resource as primary at the 
beginning, migration and all (so far, did only a few hops)

If you don''t use pygrub and specify kernel, root, etc in the config
file
then the block driver brings up the resource, but it locks up after 
migration


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