[DRBD-user] Help with initial setup

kevin kempter kevin at kevinkempterllc.com
Thu Oct 9 16:48:07 CEST 2008

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


On Oct 9, 2008, at 8:37 AM, Timh Bergström wrote:

> 2008/10/9 kevin kempter <kevin at kevinkempterllc.com>:
>>
>> On Oct 8, 2008, at 3:36 PM, Florian Haas wrote:
>>
>>> On 10/08/2008 11:04 PM, Jerry Amundson wrote:
>>>>
>>>> On Wed, Oct 8, 2008 at 3:33 PM, kevin kempter <kevin at kevinkempterllc.com 
>>>> >
>>>> wrote:
>>>>>
>>>>> 1) I setup 2 new installs of CentOS v5 (32bit) as VM's via  
>>>>> vmware server
>>>>> on
>>>>> a Dell 2900 (quad core, 16Gram, single RAID slice, etc)
>>>>>
>>>>> Note: I created /stage as a separate ext2 filesystem (mounted from
>>>>> /dev/sda2). This is the filesystem I want to replicate with drbd
>>>>
>>>> That will need to be re-made on the drbd device.
>>>
>>> Wrong. If you shrink the filesystem (resize2fs) to make room for  
>>> DRBD's
>>> metadata, you will be able to replicate the existing data without
>>> remaking the filesystem. If you need to keep that data.
>>>
>>> After you have shrunk your filesystem (shrink by 128M to be on the  
>>> safe
>>> side), you want to do exactly what your original error message  
>>> told you,
>>> namely use "drbdadm create-md <resource>" to create your metadata.
>>>
>>> Btw: ext2, being a non-journaling filesystem, is a really bad  
>>> choice for
>>> HA environments. Use ext3.
>>>
>>> Florian
>>>
>>> --
>>> : Florian G. Haas
>>> : LINBIT Information Technologies GmbH
>>> : Vivenotgasse 48, A-1120 Vienna, Austria
>>>
>>> When replying, there is no need to CC my personal address.
>>> I monitor the list on a daily basis. Thank you.
>>>
>>> LINBIT(R) and DRBD(R) are registered trademarks of LINBIT.
>>> _______________________________________________
>>> drbd-user mailing list
>>> drbd-user at lists.linbit.com
>>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>
>>
>> Hi All;
>>
>> I'm finding no luck with anything I've tried. So I've decided to go  
>> back to
>> ground zero and walk through a proper setup.  A few questions:
>>
>> I've setup 2 brand new CentOS 5 VM's (via vmware server). I'm  
>> wanting to use
>> internal meta-data to keep things simple.
>>
>> How do I need to prepare the disk ? this far I've created a partition
>> (/drbd_data) as an ext3 filesystem as part of the initial disk  
>> partitioning
>> (in the CentOS install) on both servers.  Is this correct?
>
> Why? If you do not already have any data that you want to preserve in
> this space, just dont create a filesystem on it at all, do that when
> drbd is set up and started.
>
Since I already created it, do I need to use fdisk and remove it?

>>
>> Also, do I need to unmount these /drbd_data file systems before  
>> attempting
>> to startup drbd ?
>
> It should not be mounted as it should not contain a filesystem, see  
> above.
>
>>
>>
>> Next steps:
>> 1) install the drbd RPM's on both servers
>>
>> 2) modprobe drbd (on both servers)
>>
>> 3) create the /etc/drbd.conf file on both servers
>>
>> 4) run drbdadm create-md 'resource' on the master node
>>
>> 5) run drbdadm attach 'resource' on the master node
>
> After this step, you should create the filesystem on the DRBD resource
> (ie. mkfs.ext3 (read manual for options) /dev/drbd1) not /dev/sda2.
> Then connect it - then mount the DRBD-resource. And you only have to
> create the filesystem on the master node, which will be replicated to
> the slave-node with drbd.
>
In the drbd.conf file the on resource entries (in the samples) show  
device and disk entries that are both /dev/xx I'm confused on the  
difference.
If I create an ext3 fs at /dev/sda2 how do I associate this device  
with something like /dev/drbd1 ? Is /dev/drbd1 simply the mount point ?


>>
>> 6) run drbdadm connect 'resource' on the master
>>
>>
>> Previously when I tried to run step 4 I got error messages, trying  
>> to use a
>> minimal config using internal meta data
>>
>> Does the above sound correct ? Am I missing anything ?
>>
>> Thanks in advance
>>
>>
>> _______________________________________________
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>> drbd-user at lists.linbit.com
>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>
>
>
>
> -- 
> Timh Bergström
> System Administrator
> Diino AB - www.diino.com
> :wq




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