Galera 2.x introduces a long awaited functionality: incremental state transfer. It means that if
then instead of whole state snapshot it will receive the missing writesets and catch up with the group by replaying them.
IST can dramatically speed up remerging node into cluster. It is also non-blocking on the donor.
The most important parameter for IST (besides
ist.recv_addr) is GCache size on donor. The bigger it is, the more writesets can be stored in it and the bigger seqno gaps can be closed with IST. On the other hand, if GCache is much bigger than the state size, serving IST may be less efficient than sending state snapshot.