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gnunns_175226 asked Erick Ramirez commented

Cassandra 2.1.15 in AWS moving to DSE 5.x running 3.11

Hey,

I'm looking for some general recommendations on a fairly large Cassandra data center migration. We are currently running Cassandra 2.1.15 in AWS and will be moving to DSE 5.x running 3.11. My current plan is to update 2.1.15 to 3.11 then setup replication between the two DC's. We have a lot of data, in the region of 150TB.

Any tips and tricks, best practices and potential issues we can expect would be awesome.

Thanks!

Gavin

dc migration
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Erick Ramirez answered Erick Ramirez commented

@gnunns_175226 You can directly upgrade from OSS C* 2.1 to DSE 5.0 (C* 3.0) as an interim step then onto DSE 5.1 (C* 3.11). For details on what's involved, see Upgrading from Apache Cassandra to DataStax Enterprise. Cheers!

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Erick Ramirez avatar image Erick Ramirez ♦♦ commented ·

@gnunns_175226 it isn't possible to "join" 2 separate clusters -- you'll end up with a scrambled schema (plus other issues). Given that you already have a DSE 5.1 cluster, I'd recommend just using sstableloader to load the OSS C* 2.1 data into the DSE 5.1 cluster.

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gnunns_175226 avatar image gnunns_175226 Erick Ramirez ♦♦ commented ·

Apologies, I was not clear in in my description. We have a new DC with an enterprise licensed DS cluster, completely empty. What I was looking to do is via a VPN connection add that to the existing cluster (assuming upgrade of existing cluster to the same version of c*) then decommission the original nodes once traffic has been routed to the new DC.

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Erick Ramirez avatar image Erick Ramirez ♦♦ gnunns_175226 commented ·

The same applies -- you cannot "join" the DSE cluster with the OSS C* cluster. You also cannot add DSE nodes to an existing OSS C* cluster because OSS C* doesn't know anything about parts of DSE. You really need to upgrade the OSS C* nodes to DSE and make it a DSE cluster before doing any topology changes. Cheers!

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gnunns_175226 answered

@Erick Ramirez would you recommend upgrading our AWS Cassandra cluster to DSE 5.1 before replicating over to the new DC that is currently setup with DSE 5.1. I believe we can do a direct rolling upgrade of C*2.1 to C*3.11 and then join the clusters which might cut out the interim step.

I'm trying to work out the best way to minimize risk for the migration, because as usual we need to do this with close to zero down time.

Thanks

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