*: highlight "--unsafe-overwrite-db" flag

Signed-off-by: Gyuho Lee <[email protected]>

CHANGELOG-3.2.md

@@ -38,6 +38,13 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.16...v3.2.17) and
   - Server now returns `rpctypes.ErrLeaseTTLTooLarge` to client, when the requested `TTL` is larger than *9,000,000,000 seconds* (which is >285 years).
   - Again, etcd `Lease` is meant for short-periodic keepalives or sessions, in the range of seconds or minutes. Not for hours or days!
 - Enable etcd server [`raft.Config.CheckQuorum` when starting with `ForceNewCluster`](https://github.com/coreos/etcd/pull/9347).
+- Add [`etcd --unsafe-overwrite-db`](https://github.com/coreos/etcd/pull/9484) flag, to support [migration from v2 with no v3 data](https://github.com/coreos/etcd/issues/9480).
+  - etcd server panics if it tries to restore from existing snapshots but no v3 `ETCD_DATA_DIR/member/snap/db` file.
+  - This happens when the server had migrated from v2 with no previous v3 data.
+  - This is to prevent accidental v3 data loss (e.g. `db` file might have been moved).
+  - With `--unsafe-overwrite-db` enabled, etcd allows to create a fresh `db` file on reboot, when there are existing snapshots.
+  - Use it only for v2 migration. Otherwise, previous v3 data could be overwritten with existing snapshots.
+  - This flag will be dropped in v4.
 
 ### Go
 

CHANGELOG-3.3.md

@@ -19,6 +19,16 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.3.2...v3.3.3) and [
   - For instance, when hourly writes are 100 and `--auto-compaction-mode=periodic --auto-compaction-retention=24h`, `v3.2.x`, `v3.3.0`, `v3.3.1`, and `v3.3.2` compact revision 2400, 2640, and 2880 for every 2.4-hour, while `v3.3.3` *or later* compacts revision 2400, 2500, 2600 for every 1-hour.
   - Futhermore, when `--auto-compaction-mode=periodic --auto-compaction-retention=30m` and writes per minute are about 1000, `v3.3.0`, `v3.3.1`, and `v3.3.2` compact revision 30000, 33000, and 36000, for every 3-minute, while `v3.3.3` *or later* compacts revision 30000, 60000, and 90000, for every 30-minute.
 
+### Fixed: v3
+
+- Add [`etcd --unsafe-overwrite-db`](https://github.com/coreos/etcd/pull/9484) flag, to support [migration from v2 with no v3 data](https://github.com/coreos/etcd/issues/9480).
+  - etcd server panics if it tries to restore from existing snapshots but no v3 `ETCD_DATA_DIR/member/snap/db` file.
+  - This happens when the server had migrated from v2 with no previous v3 data.
+  - This is to prevent accidental v3 data loss (e.g. `db` file might have been moved).
+  - With `--unsafe-overwrite-db` enabled, etcd allows to create a fresh `db` file on reboot, when there are existing snapshots.
+  - Use it only for v2 migration. Otherwise, previous v3 data could be overwritten with existing snapshots.
+  - This flag will be dropped in v4.
+
 ### Metrics, Monitoring
 
 - Add missing [`etcd_network_peer_sent_failures_total` count](https://github.com/coreos/etcd/pull/9437).

CHANGELOG-3.4.md

@@ -93,6 +93,13 @@ See [security doc](https://github.com/coreos/etcd/blob/master/Documentation/op-g
   - For instance, a flaky(or rejoining) member may drop in and out, and start campaign. This member will end up with a higher term, and ignore all incoming messages with lower term. In this case, a new leader eventually need to get elected, thus disruptive to cluster availability. Raft implements Pre-Vote phase to prevent this kind of disruptions. If enabled, Raft runs an additional phase of election to check if pre-candidate can get enough votes to win an election.
   - `--pre-vote=false` by default.
   - v3.5 will enable `--pre-vote=true` by default.
+- Add [`--unsafe-overwrite-db`](https://github.com/coreos/etcd/pull/9484) flag, to support [migration from v2 with no v3 data](https://github.com/coreos/etcd/issues/9480).
+  - etcd server panics if it tries to restore from existing snapshots but no v3 `ETCD_DATA_DIR/member/snap/db` file.
+  - This happens when the server had migrated from v2 with no previous v3 data.
+  - This is to prevent accidental v3 data loss (e.g. `db` file might have been moved).
+  - With `--unsafe-overwrite-db` enabled, etcd allows to create a fresh `db` file on reboot, when there are existing snapshots.
+  - Use it only for v2 migration. Otherwise, previous v3 data could be overwritten with existing snapshots.
+  - This flag will be dropped in v4.
 - TODO: [`--initial-corrupt-check`](TODO) flag is now stable (`--experimental-initial-corrupt-check` is deprecated).
   - `--initial-corrupt-check=true` by default, to check cluster database hashes before serving client/peer traffic.
 - TODO: [`--corrupt-check-time`](TODO) flag is now stable (`--experimental-corrupt-check-time` is deprecated).

Documentation/upgrades/upgrade_3_2.md

@@ -212,6 +212,8 @@ See [issue #6336](https://github.com/coreos/etcd/issues/6336) for more contexts.
 
 ### Server upgrade checklists
 
+**NOTE:** `v3.2.18` added [`etcd --unsafe-overwrite-db`](https://github.com/coreos/etcd/pull/9484) flag, to support [migration from v2 with no v3 data](https://github.com/coreos/etcd/issues/9480). etcd server panics if it tries to restore from existing snapshots but no v3 `ETCD_DATA_DIR/member/snap/db` file. This happens when the server had migrated from v2 with no previous v3 data. This is to prevent accidental v3 data loss (e.g. `db` file might have been moved). With `--unsafe-overwrite-db` enabled, etcd allows to create a fresh `db` file on reboot, when there are existing snapshots. Use it only for v2 migration. Otherwise, previous v3 data could be overwritten with existing snapshots. This flag will be dropped in v4.
+
 #### Upgrade requirements
 
 To upgrade an existing etcd deployment to 3.2, the running cluster must be 3.1 or greater. If it's before 3.1, please [upgrade to 3.1](upgrade_3_1.md) before upgrading to 3.2.