Elasticsearch change primary shards number

Elastic Stack Elasticsearch
1

Hello! i have 3 node elasticsearch cluster and i have index with
1 primary and 1 replica shards
so i want to change the primary shard number from 1 to 2 using this method Split index API | Elasticsearch Guide [7.9] | Elastic but in the doc said that

The number of primary shards in the target index must be a multiple of the number of primary shards in the source index

but in my case 1 * 1 = 1
so how can i do resize from 1 primary shards to 2 primary shards correctly?

2

2 is a multiple of 1 so that is fine. Since you are splitting shards they all need to split the same way. You can split a single shard into 2, 3 or 4 etc shards, but can e.g. not go from 2 to 3 or from 2 to 5.

3

Thanks! and it is save to delete original index after the split completion?