Alternative approach to setting up new DC

[Jens Rantil <je...@tink.se>]

Hi,

I am provisioning a new datacenter for an existing cluster. A rather shaky
VPN connection is hindering me from making a "nodetool rebuild" bootstrap
on the new DC. Interestingly, I have a full fresh database snapshot/backup
at the same location as the new DC (transferred outside of the VPN). I am
now considering the following approach:

   1. Make sure my clients are using the old DC.
   2. Provision the new nodes in new DC.
   3. ALTER the keyspace to enable replicas on the new DC. This will start
   replicating all writes from old DC to new DC.
   4. Before gc_grace_seconds after operation 3) above, use sstableloader
   to stream my backup to the new nodes.
   5. For safety precaution, do a full repair.

Could you see any issues with doing this?

Cheers,
Jens
-- 

Jens Rantil
Backend Developer @ Tink

Tink AB, Wallingatan 5, 111 60 Stockholm, Sweden
For urgent matters you can reach me at +46-708-84 18 32.

Re: Alternative approach to setting up new DC

[Jens Rantil <je...@tink.se>]

Hi,

I never got any response here, but just wanted to share that I went to a
Cassandra meet-up in Stockholm yesterday where I talked to two knowledgable
Cassandra people that verified that the approach below should work. The
most important thing is that the backup must be fully imported before
gc_grace_seconds after when the backup is taken.

As of me, I managed to a get a more stable VPN setup and did not have to go
down this path.

Cheers,
Jens

On Mon, Apr 18, 2016 at 10:15 AM Jens Rantil <je...@tink.se> wrote:

> Hi,
>
> I am provisioning a new datacenter for an existing cluster. A rather shaky
> VPN connection is hindering me from making a "nodetool rebuild" bootstrap
> on the new DC. Interestingly, I have a full fresh database snapshot/backup
> at the same location as the new DC (transferred outside of the VPN). I am
> now considering the following approach:
>
>    1. Make sure my clients are using the old DC.
>    2. Provision the new nodes in new DC.
>    3. ALTER the keyspace to enable replicas on the new DC. This will
>    start replicating all writes from old DC to new DC.
>    4. Before gc_grace_seconds after operation 3) above, use sstableloader
>    to stream my backup to the new nodes.
>    5. For safety precaution, do a full repair.
>
> Could you see any issues with doing this?
>
> Cheers,
> Jens
> --
>
> Jens Rantil
> Backend Developer @ Tink
>
> Tink AB, Wallingatan 5, 111 60 Stockholm, Sweden
> For urgent matters you can reach me at +46-708-84 18 32.
>
-- 

Jens Rantil
Backend Developer @ Tink

Tink AB, Wallingatan 5, 111 60 Stockholm, Sweden
For urgent matters you can reach me at +46-708-84 18 32.