Is Secondary namenode needed in Hadoop 2.x?

Question

big data

I am studying Hadoop technology to deploy the appropriate cluster, in connection with this, a question arose
in the architecture of the Hadoop 1.x cluster, Secondary Namenode appears which contains fsimage and edits changes.
Considering the architecture of Hadoop 2.x using the example of Hortonworks, I saw that instead of Secondary Namenode, the concept of Standby Namenode is used, which is a full-fledged standby (in case the main node crashes, it takes control).
Now the questions are:
1) Does hadoop 2.x use Standby Namenode instead of Secondary Namenode ? or is this also? 2) The performance of a hadoop cluster depends on the presence of a Secondary (Standby) Namenode ?
3) Is it possible to deploy a pilot project without a Secondary (Standby) Namenode ?
Thanks

Answer 1

Received an answer from other sources
1) since Hadoop 2.x it became possible to use a full-fledged StandBy instead of Secondary Namenode, since it is a full-fledged standby and can be used if the main node crashes. while the Secondary Namenode is used to restore the main node according to the logs that are written to it
2) Does not affect performance
3) Yes, you can, but in case of problems with the main node, it will be impossible to restore the cluster