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  • Zenifer Cheruveettil thinks this is interesting:

The disadvantage is that if the synchronous follower doesn’t respond (because it has crashed, or there is a network fault, or for any other reason), the write cannot be processed. The leader must block all writes and wait until the synchronous replica is available again.

From

Cover of Designing Data-Intensive Applications

Note

Latency Vs. Consistency tradeoff; see also PACELC theorem