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In commitc82250e0cf(gossip: Allow deferring advertise of local node to be up), the replacing node is changed to postpone the responding of gossip echo message to avoid other nodes sending read requests to the replacing node. It works as following: 1) replacing node does not respond echo message to avoid other nodes to mark replacing node as alive 2) replacing node advertises hibernate state so other nodes knows replacing node is replacing 3) replacing node responds echo message so other nodes can mark replacing node as alive This is problematic because after step 2, the existing nodes in the cluster will start to send writes to the replacing node, but at this time it is possible that existing nodes haven't marked the replacing node as alive, thus failing the write request unnecessarily. For instance, we saw the following errors in issue #8013 (Cassandra stress fails to achieve consistency when only one of the nodes is down) ``` scylla: [shard 1] consistency - Live nodes 2 do not satisfy ConsistencyLevel (2 required, 1 pending, live_endpoints={127.0.0.2, 127.0.0.1}, pending_endpoints={127.0.0.3}) [shard 0] gossip - Fail to send EchoMessage to 127.0.0.3: std::runtime_error (Not ready to respond gossip echo message) c-s: java.io.IOException: Operation x10 on key(s) [4c4f4d37324c35304c30]: Error executing: (UnavailableException): Not enough replicas available for query at consistency QUORUM (2 required but only 1 alive ``` To solve this problem for older releases without the patch "repair: Switch to use NODE_OPS_CMD for replace operation", a minimum fix is implemented in this patch. Once existing nodes learn the replacing node is in HIBERNATE state, they add the replacing as replacing, but only add the replacing to the pending list only after the replacing node is marked as alive. With this patch, when the existing nodes start to write to the replacing node, the replacing node is already alive. Tests: replace_address_test.py:TestReplaceAddress.replace_node_same_ip_test + manual test Fixes: #8013 Closes #8614 (cherry picked from commite4872a78b5)