[DRBD-user] Does DRBD 8 use more space for meta data than DRBD 0.7?

Lars Ellenberg lars.ellenberg at linbit.com
Fri Jan 30 10:29:29 CET 2009


On Thu, Jan 29, 2009 at 08:54:53AM -0800, John Du wrote:
> Lars Ellenberg wrote:
>> please do not hijack threads.
>>
>> On Wed, Jan 28, 2009 at 08:51:02AM -0800, John Du wrote:
>>   
>>> Hi,
>>>
>>> I am trying to upgrade DRBD 0.7 to 8.3.0.  When running "drbdadm   
>>> create-md", I get an exit code 40 indicating there is not enough 
>>> space  on the disk used for DRBD to store the meta data.  My question 
>>> is why  DRBD 0.7 has enough space on the same disk but DRBD 8 does 
>>> not?
>>>     
>>
>> probably because drbd 0.7 just was not paranoid enough,
>> and did not have so many sanity checks.
>> we added those sanity checks,
>> because people kept shooting themselves in the foot.
>>
>> show us the exact message you get from create-md.
>>
>> is it "internal" or "external" meta data?
>>
>> what exactly is the size of the lower level device?
>> (cat /proc/partitions)
>>
>> my guess is, without further information,
>> that you created a file system on the lower level device,
>> then overwrote the last few MB of it with "internal" drbd meta data.
>>
>>   
>
> Thanks for the information:  DRBD 8 cannot convert all the existing 0.7  
> devices without losing the existing data or adding an external meta data  
> device.

absolutely _wrong_.

it "just" refuses to continue with a corrupted setup.

which is a good thing.

> Yes.  The DRBD device with internal meta data was built on an existing  
> file system.

which you forgot to shrink first.
so you corrupted it.
and you are just lucky that the file system did not notice so far.


-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
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