Reference Solution
Step 1 — Assess the cluster state
nodetool status
# → Status/State shows:
# UN 10.10.1.1 ... <uuid-node0>
# DN 10.10.1.2 ... <uuid-node1> ← dead node
# UN 10.10.1.3 ... <uuid-node2>
Note the UUID in the last column of the DN row — this is node1's Host ID.
Step 2 — Confirm node1 is unreachable
ssh -o ConnectTimeout=10 node1
# → ssh: connect to host node1 port 22: Connection timed out
# Confirmed: no SSH access, no recovery possible
Step 3 — Remove the dead node from the ring
# Extract the Host ID automatically
HOST_ID=$(nodetool status | grep '^DN' | awk '{print $(NF-1)}')
echo "Removing host: $HOST_ID"
nodetool removenode "$HOST_ID"
# Output: "RemovalStatus=COMPLETED" (may take 30–120s while data streams)
removenode evicts the dead node's token ranges and streams any data it exclusively held to the surviving nodes. Unlike decommission, it does not require the node to be running.
Step 4 — Verify ring is clean
nodetool status
# → Exactly 2 UN nodes, 0 DN nodes:
# UN 10.10.1.1 ...
# UN 10.10.1.3 ...
Step 5 — Verify data integrity at QUORUM
cqlsh 10.10.1.1 -e "CONSISTENCY QUORUM; SELECT COUNT(*) FROM bench.kv;"
# → 5
cqlsh 10.10.1.3 -e "CONSISTENCY QUORUM; SELECT COUNT(*) FROM bench.kv;"
# → 5
QUORUM with RF=3 requires ceil(3/2) = 2 responses. Both surviving nodes hold complete replicas after removenode streaming, so QUORUM reads are satisfied.
Step 6 — Repair (best practice)
nodetool repair bench
# Wait for: "Repair command #N finished" in /var/log/cassandra/debug.log
After removenode, repair runs Merkle-tree anti-entropy between the two surviving nodes to eliminate any remaining inconsistencies.
Root Cause Summary
node1 suffered a complete hardware failure — both its cluster NIC and OS-level SSH daemon became unreachable. This is distinct from the NIC split-brain scenario: there is no OS running to accept ip link set up, no IPMI BMC accessible to power the node back on. The only correct response is to treat the node as permanently dead and remove it from the Cassandra ring via nodetool removenode.
Key Concepts
| Operation | When to use | Node state required |
|---|---|---|
nodetool decommission |
Planned removal (node is healthy) | Node must be UP and reachable |
nodetool removenode <HOST_ID> |
Emergency removal (node is dead) | Node must be DN or unreachable |
Why not decommission? It streams data from the leaving node, which requires the node to be running and reachable over the cluster network. Since node1's cluster NIC is down and SSH is blocked, decommission would hang indefinitely.
Why QUORUM still works? With RF=3 and 2 surviving nodes, each row has 2 physical replicas. QUORUM requires ceil(RF/2) = 2 replicas — exactly what we have. Once removenode completes its streaming pass, both survivors are guaranteed to hold every row.