Can sst_state_transfer be set to rsync with innodb as storage engine in Galera cluster?
Is xtrabackup the only wsrep-sst-method to be used with innodb storage engine?


All Galera clusters are InnoDB, MyISAM (and derivates) not supported (expect mysql database with wrappers for managing users/permissions).

No, nothing wrong with your configuration. You can use Logical State Snapshot mysqldump or the Physical State Snapshot rsync and xtrabackup. See State Snapshot Transfers for a comparison.

A physical restore always needs a restart. The same concept like backup/restore.

In normal operations only IST is needed. SST is only needed when something goes wrong (maybe infrastructure issue) and the node is out-of-sync. Mostly the DBA cares about such cases.


State Snapshot Transfers (SST) Where a snapshot of the entire node
state transfers.
Incremental State Transfers (IST) Where only the missing transactions transfer.