Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi Lars,
I configured it with md raid (and write-mostly) for local mirroring and DRBD for the remote replication. Works perfectly!
Thank you,
Senne Vaeyens
On 09 Jul 2014, at 09:47, Lars Ellenberg <lars.ellenberg at linbit.com> wrote:
> On Wed, Jul 09, 2014 at 09:40:59AM +0200, Lars Ellenberg wrote:
>> On Wed, Jul 09, 2014 at 09:26:49AM +0200, Lars Ellenberg wrote:
>>> On Wed, Jul 09, 2014 at 01:58:05AM +0000, Senne Vaeyens wrote:
>>>> Hi,
>>>>
>>>> I’m using 8.4.4 on CentOS 6.5
>>>> I try to configure an NFS server as explained by Craig Carl in the
>>>> following presentation:
>>>> http://www.slideshare.net/AmazonWebServices/nfs-and-cifs-options-for-aws-stg401-aws-reinvent-2013
>>>> , (youtube video of the presentation can be found here:
>>>> https://www.youtube.com/watch?v=xbuiIwEOCAs)
>>>
>>> Yeah, well, IMO, that is tecnically nonsense.
>>
>> Ok, that may come accross as rude or harsh.
>>
>> What I mean is, DRBD is NOT a host based mirroring solution,
>> but a replication solution, which is not the same thing.
>>
>> If you want to do host based mirroring, use md raid.
>>
>> If you want to do replication, between instances,
>> use DRBD.
>>
>> You can clearly use DRBD to *replicate* from one instance
>> in one zone to an other instance in an other zone,
>> or from instance on "fast" storage to instance on "durable" storage.
>>
>> This makes perfectly sense.
>> This is what DRBD was designed for.
>
> And, now that I watched the video,
> that is even what Craig actually suggests to do.
> Replicating from one instance in zone a to an other instance in zone b.
>
> So do that ;-)
>
> But don't believe what he says about oos (out-of-sync).
> IF you have "oos" != 0 in /proc/drbd,
> you are not "behind",
> but the respective target volume is *inconsistent* for that many blocks.
>
>> But, in my opinion, you should not try to use DRBD to "mirror" from one
>> block storage to an other block storage *within the same instance*.
>> For that, md raid would likely be the better solution.
>> That is what md raid has been designed for.
>>
>> I'm clearly biased towards DRBD,
>> and I'm happy to hear that you all like to use DRBD.
>> But, even if it can do something,
>> it is not always the best fit.
>> Not for everything.
>>
>> Simply use the right tool for the job.
>>
>>>> Craig explains on slide 12 how you configure a local mirror with brbd;
>>>>
>>>> It goes somewhat like this...
>>>>
>>>> resource r0 {
>>>> on az-a{
>>>> device /dev/drbd0;
>>>> disk /dev/md0;
>>>> address 10.1.1.1:7789;
>>>> meta-disk internal;
>>>> }
>>>> on az-a{
>>>> device /dev/drbd1;
>>>> disk /dev/md1;
>>>> address 10.1.1.1:7789;
>>>> meta-disk internal;
>>>> }
>>>> }
>>>
>>> Which is simply wrong and won't even parse.
>>> So why don't you ask Craig how he really did it?
>>> Clearly not the way he presented it in those slides.
>>>
>>> But see there:
>>> http://www.gossamer-threads.com/lists/drbd/users/26473#26473
>>>
>>> Still, it does not make sense.
>>> DRBD is the wrong tool for the job.
>>> Use md raid for host based mirroring.
>>>
>>>
>>> --
>>> : 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.
>>> __
>>> please don't Cc me, but send to list -- I'm subscribed
>>> _______________________________________________
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>>> drbd-user at lists.linbit.com
>>> http://lists.linbit.com/mailman/listinfo/drbd-user
>>
>> --
>> : 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.
>> __
>> please don't Cc me, but send to list -- I'm subscribed
>> _______________________________________________
>> drbd-user mailing list
>> drbd-user at lists.linbit.com
>> http://lists.linbit.com/mailman/listinfo/drbd-user
>
> --
> : 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.
> __
> please don't Cc me, but send to list -- I'm subscribed
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user