All very good advice, but I just wanted to jump in and suggest that it really might be worthwhile getting some paid support from linbit, even if just to help migrate the system until it's live and stable. I've personally used the paid support option (I paid for one year) and even though I only needed help 2 or 3 times, it was well worth the money spent. The first was related to the initial setup/configuration where I had not provisioned hardware properly, and they sorted the DRBD config to compensate, and the other one or two times were basically disasters, where it's so much better to get professional (and quick) advice rather than trying to muddle through unfamiliar territory.

Just my thoughts.

Regards,
Adam

On 06/10/17 08:58, Digimer wrote:
Good fencing prevents split-brains, period. Setup pacemaker, setup and
test stonith, configure DRBD to use 'fencing resource-and-stonith;' and
enable the crm-{un,}fence-peer.sh' {un,}fence-handlers. The setup
pacemaker to colocate the DRBD resource -> FS -> IP.

digimer

On 2017-10-05 05:01 PM, José Andrés Matamoros Guevara wrote:
Don't know yet. Thinking about using pacemaker, for high availability. But have 
a manually recovery to avoid split brain - corruption data situations. Maybe we 
are going to use three-four servers to have a disaster recovery site.

Andres.

-----Original Message-----
From: Digimer [mailto:[email protected]]
Sent: Thursday, 5 October, 2017 12:43 PM
To: José Andrés Matamoros Guevara <[email protected]>; 
[email protected]
Subject: Re: [DRBD-user] Moving TeraBytes to drbd device

Will you be using pacemaker for auto-recovery, or are you planning to do fully 
manual recovery?

digimer

On 2017-10-05 12:19 PM, José Andrés Matamoros Guevara wrote:
OK. That's a procedure I have thought about, but didn't know if there were 
another more effective. I just have to check how much data I have to sync 
during the window.

Last question: what kind of test do you recommend to check the new drbd system? 
I have configure a few systems but never this important.

Thanks again,

Andres.


-----Original Message-----
From: Digimer [mailto:[email protected]]
Sent: Wednesday, 4 October, 2017 11:11 PM
To: José Andrés Matamoros Guevara <[email protected]>;
[email protected]
Subject: Re: [DRBD-user] Moving TeraBytes to drbd device

If it were up to me, given what I understand of your requirements (which is 
minimal), I'd look at setting up the new DRBD system. Test it carefully and 
when ready, do an rsync to get the bulk data over. When your windows opens, 
re-run the rsync to copy just what's changed.

If you're asking how to setup a DRBD based system, we'll need to know more 
about what you want the system to do.

cheers,

digimer

On 2017-10-04 11:29 PM, José Andrés Matamoros Guevara wrote:
Thanks for your answer.

Yes, I need to copy a SAN to a new drbd system. And yes, I'll check
with LinBit for support if I don't find a safe solution for myself.

Just a question: I have been looking through the LinBit documents and
haven't found exactly what I was looking for. If you can point me
about what document/documents or topics I have to read about, will be great.

Thanks for the info.

Andres.

-----Original Message-----
From: Digimer [mailto:[email protected]]
Sent: Tuesday, 3 October, 2017 6:10 PM
To: José Andrés Matamoros Guevara <[email protected]>;
[email protected]
Subject: Re: [DRBD-user] Moving TeraBytes to drbd device

On 2017-10-03 06:57 PM, José Andrés Matamoros Guevara wrote:
I have been consulted about moving multiple Terabytes to a new
system using drbd to ensure high availability. I have been thinking
on multiple scenarios to move the data as fast as I can and to have
a minimal maintenance window to change the systems.

Is there any how-to or recommendation about it? I know it is not
exactly a drbd consult but I supposed you have been using it for a
while and have more idea about a best practice. I have thought to
have a backup program to copy the data and then update it during the
maintenance window, but been lots of TB, the reading/writing data
time is going to be the factor to consider.

Thanks in advance and best regards, Andres.
The best answer is to engage LINBIT for commercial support if you've
been tasked with a sensitive project and a minimal window to do it in.

That said, I'll share what comes to mind;

If you mean "move" as in "copy the data to a new system that already
has DRBD configured and tested", then it is merely a question of hardware.
Make sure you have a sufficiently fast new system to accept the
incoming volume of data within the prescribed time frame. DRBD itself
has minimal overhead, so it is really a question of the speed of the
disks and the replication link.

If you mean to convert an existing filesystem on existing hardware to
be backed by DRBD, then you need to either grow the backing storage
by ~32MiB per TiB of existing data, or setup a matching sized storage
device and configure external metadata. With that extra space, you
can setup DRBD and it will see the existing FS and data fine. You'll
need a full resync to the new peer, of course. Also, test/practice
outside prod thoroughly to be certain you have the steps down pat.

There are docs on how to do this openly available on LINBIT's website.
If you get stuck on certain steps, post specific questions and we'll help.

--
Digimer
Papers and Projects: https://alteeve.com/w/ "I am, somehow, less
interested in the weight and convolutions of Einstein’s brain than in
the near certainty that people of equal talent have lived and died in
cotton fields and sweatshops." - Stephen Jay Gould


--
Digimer
Papers and Projects: https://alteeve.com/w/ "I am, somehow, less
interested in the weight and convolutions of Einstein’s brain than in
the near certainty that people of equal talent have lived and died in
cotton fields and sweatshops." - Stephen Jay Gould


--
Digimer
Papers and Projects: https://alteeve.com/w/ "I am, somehow, less interested in the 
weight and convolutions of Einstein’s brain than in the near certainty that people of 
equal talent have lived and died in cotton fields and sweatshops." - Stephen Jay 
Gould



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