The advice so far is exactly correct for an in-place kind of upgrade. The blog
post you mentioned is different. They decided to jump versions in Cassandra by
standing up a new cluster and using a dual-write/dual-read process for their
app. They also wrote code to read and interpret sstables in order to migrate
existing data. Getting that right with compaction running, data consistency,
etc. it not easy. That is what Cassandra does, of course. They had to reverse
engineer that process.
I would not personally take that path as it seems a more difficult way to go --
for the DBA/admin. It is a nice path for the development team, though. They
only had to look at their reads and writes (already encapsulated in a DAO) for
the dual clusters. In a multi-upgrade scenario, drivers and statements probably
have to get upgraded at several steps along the way (including a move from
Thrift to CQL, probably). More app testing is required each upgrade. So, the
decision has to be based on which resources you have and trust (app dev and
testing + Cassandra upgrades or data migration and testing). Once you have
automated/semi-automated Cassandra upgrades in place, that is an easier path,
but that company obviously hadn't invested there.
Sean Durity
-Original Message-
From: Michael Shuler On Behalf Of Michael Shuler
Sent: Monday, June 17, 2019 8:26 AM
To: user@cassandra.apache.org
Subject: [EXTERNAL] Re: Cassandra migration from 1.25 to 3.x
First and foremost, read NEWS.txt from your current version to the version you
wish to upgrade to. There are too may details that you many need to be aware
of. For instance, in the 2.0.0 Upgrading notes:
https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_apache_cassandra_blob_cassandra-2D3.11_NEWS.txt-23L1169-2DL1178=DwIDaQ=MtgQEAMQGqekjTjiAhkudQ=aC_gxC6z_4f9GLlbWiKzHm1vucZTtVYWDDvyLkh8IaQ=CPWy2XBaDFHzVDapNO4E7kLIFFfbkRd8KqftSrypjSU=D3Y18E9gxewpushCMETjHt9cS8lKvLMrhUdhPriF4Dk=
I assume you meant 1.2.5, so you're first step is to upgrade to at least
1.2.9 (I would suggest using latest 1.2.x, which is 1.2.19). Then you can to to
2.0.x and up.
Practicing on a scratch cluster is valuable experience. Reading the upgrade
notes in NEWS.txt is a must.
--
Kind regards,
Michael
On 6/17/19 3:34 AM, Anurag Sharma wrote:
> Thanks Alex,
>
> I came across some interesting and efficient ways of upgrading from
> 1.x to 3.x as described in the blog here
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__medium.com_-40ro
> eezilkha_database-2Dmigration-2Dat-2Dscale-2Dae85c14c3621=DwIDaQ=M
> tgQEAMQGqekjTjiAhkudQ=aC_gxC6z_4f9GLlbWiKzHm1vucZTtVYWDDvyLkh8IaQ=
> CPWy2XBaDFHzVDapNO4E7kLIFFfbkRd8KqftSrypjSU=7ekpEXHT1Qm_xL9l6_1Kty32
> fDDerlB_PgO1-4K1-VQ= > and others. Was curious if someone has
> open-sourced their custom utility. :D
>
> Regards
> Anurag
>
> On Mon, Jun 17, 2019 at 1:27 PM Oleksandr Shulgin
> mailto:oleksandr.shul...@zalando.de>> wrote:
>
> On Mon, Jun 17, 2019 at 9:30 AM Anurag Sharma
> mailto:anurag.rp.sha...@gmail.com>> wrote:
>
>
> We are upgrading Cassandra from 1.25 to 3.X. Just curious if
> there is any recommended open source utility for the same.
>
>
> Hi,
>
> The "recommended open source utility" is the Apache Cassandra
> itself. ;-)
>
> Given the huge difference between the major versions, though, you
> will need a decent amount of planning and preparation to
> successfully complete such a migration. Most likely you will want
> to do it in small steps, first upgrading to the latest minor version
> in the 1.x series, then making a jump to 2.x, then to 3.0, and only
> then to 3.x if you really mean to. On each upgrade step, be sure to
> examine the release notes carefully to understand if there is any
> impact for your cluster and/or client applications. Do have a test
> system with preferably identical setup and configuration and execute
> the upgrade steps there first to verify your expectations.
>
> Good luck!
> --
> Alex
>
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