Upgrade ElasticSearh from 5.5 to 7.1

Elastic Stack Elasticsearch
1

Hi,

I am looking to upgrade and migrate from elasticsearch 5.5 to 7.1. Wanted to understand, Is this possible and if yes then do we need to do a rolling update to intermediate version.

Also do you have any compatibility matrix between different version.

2

You will need to reindex as data created with a 5.x can't be read as is by a 7.x version.

3

Thanks. But is it possible to upgrade directly from 5.5 to 7.1 version? And when you say reindex, does it mean we have to delete the index (Created following the index pattern) and then recreating them in the newer version?

4

No.

Yes. But you can use the reindex API to help you doing this.

Otherwise, you need to:

  • Upgrade to 5.6.16
  • Use the upgrade assistant to check what needs to be done
  • Upgrade to 6.8.6
  • Use the upgrade assistant to check what needs to be done
  • Upgrade to 7.x. I'd recommend 7.5.2 as this is the latest one.
5

Thanks @dadoonet for reply and It really help to clarify many stuff.

So just to reiterate for my confirmation

• Reindex and Upgrade to 5.6.16
•Use the upgrade assistant to check what needs to be done
•Upgrade to 6.8.6
•Use the upgrade assistant to check what needs to be done
•Upgrade to 7.x. I'd recommend 7.5.2 as this is the latest one.

  1. When we are reindexing using api then I believe the will belong to target or destination elastic search.
  2. Is it possible to back out the change (back to 5.5 version in case of any issue?

Apologies in case my questions are too basic. I will be doing this for the first time?

6

I answered in Upgrade Rollback

7

Using reindex, and specifically reindex from remote feature is helpful to directly go from a old version to a new one and benefit from all the optimisations that happened in the meantime.

8

when we say reindex, shall we directly reindex to 7.x version or shall we take step wise approach like

  1. reindex 5.5 to 5.6, then upgrade
  2. reindex 5.6 to 6.8 then upgrade( I don't think reindex is required here as per the documentation, but still correct me if m wrong)
  3. reindex 6.8 to 7.x, then upgrade

Second approach
Directly reindex to 7.x version

Secondly can you help me understand the difference in two approaches of upgrade
1: Rolling upgrade
2: Restart upgrade

9

You need to reindex once you get to 6.8, not while on version 5.x.

10

I'd probably try this:

11

Thanks both for the answers.

Can you please suggest something on the other part of the question, which is

"Secondly can you help me understand the difference in two approaches of upgrade"
1: Rolling upgrade
2: Restart upgrade

Is it recommended to go for (my understanding by reading the docs though it get confusing at times)

  1. 5.5 to 5.6 - rolling upgrade
  2. 5.6 to 6.8 - full cluster restart
  3. 6.8 to 7.1 - rolling upgrade

or can we choose between either of them as it doesn't make much difference.

12

Full cluster restart means that all nodes are down and you can't serve your users anymore during the shutdown period. But it's safer, easier IMO.
Rolling upgrade means that your cluster is still operational while changing the version.

13

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