[DRBD-user] Upgrade problem with 0.8

Lars Ellenberg lars.ellenberg at linbit.com
Thu Apr 23 11:22:23 CEST 2009

On Thu, Apr 23, 2009 at 10:50:22AM +0200, Christian Iversen wrote:
> Lars Ellenberg wrote:
>> On Wed, Apr 22, 2009 at 05:16:19PM +0200, Christian Iversen wrote:
>>> Hi all
>>> We're trying to upgrade our 0.7 DRBD disks to 0.8.
>> no.
>> you are not.
>> there is no such thing as drbd 0.8
>> there is only drbd 8.0.x (currently: 8.0.16)
>> and 8.3.y (currently 8.3.1).
> Ah, I didn't notice the jump there :)
> In that case, I've tried with 8.0.14. After the original post, I also  
> tried with 8.3.1, which had a similar message, although distinct.
>>> We're running 2 machines, ares and athena, in a heartbeat-failover  
>>> cluster. We've been following this guide:
>>> http://fghaas.wordpress.com/2007/10/03/step-by-step-upgrade-from-drbd-07-to-drbd-8/
>>> step-by-step.
>>> However, we get this rather ominous warning when doing the "drbdadm  
>>> create-md" step:
>>>  > md_offset 310068375552
>>>  > al_offset 310068342784
>>>  > bm_offset 310058876928
>>>  >
>>>  > Found ext3 filesystem which uses 302670080 kB
>>>  > current configuration leaves usable 302791872 kB
>>>  >
>>>  >  ==> This might destroy existing data! <==
>>>  >
>>>  > Do you want to proceed?
>>>  > [need to type 'yes' to confirm]
>>> After looking at the kB sizes, it seems there are 118.9375 MB space 
>>> left for meta-data. Maybe this is not sufficient?
>> and if you had used one of these mentioned "latest" releases of DRBD,
>> this message would have already been softened, as it apparently scared
>> too many people (including you).
> Well, it sure did :-)
> By the way, is there some way for me to know that this step should be  
> safe? Can I figure it out by looking at the offsets and the kB-sizes?

for ext3, DRBDs "guess" usually is pretty good.
so if it says "ext3 uses X", and "current config leaves usable Y",
and "X < Y", then in general you are good.

for internal meta data, if you have been ok before,
you are ok after upgrade to DRBD 8,
because DRBD 8 internal meta data in general uses less space.
(it may use more, but only for configurations that had not been
 possible with 0.7, namely >= 4TiB)

it may happen though, that you know you actually use your drbd with some
homegrown binary format, and the first few sectors somehow happen to
look like an ext3 superblock, and drbdmeta gets it all wrong.
if it says ext3 found, but you know you were using it raw, or jfs, or
the file system from the master thesis of the brother of your
girlfriends best friend,
then you should go eek, no, there is something wrong...

>> the softened message reads
>>   Even though it looks like this would place the new meta data into
>>   unused space, you still need to confirm, as this is only a guess.
>> so you are good, your data is fine,
>> you may proceed.
>> 	:)
> Thank you very much. DRBD is excellent :-)

glad to hear that.

sometimes one forgets that in general people tend to post on mailing
lists only when having problems or otherwise feeling the need to
complain about something.


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

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