Documentation/upgrades: clean up snapshot change doc

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>
This commit is contained in:
Gyuho Lee 2018-04-20 14:26:45 -07:00
parent dab54fab3f
commit e23ee1a1a7

View File

@ -14,7 +14,9 @@ Highlighted breaking changes in 3.2.
#### Change in default `snapshot-count` value
The default value of `--snapshot-count` has [changed from from 10,000 to 100,000](https://github.com/coreos/etcd/pull/7160). Higher snapshot count means it holds Raft entries in memory for longer before discarding old entries. It is a trade-off between less frequent snapshotting and [higher memory usage](https://github.com/kubernetes/kubernetes/issues/60589#issuecomment-371977156). Higher `--snapshot-count` will be manifested with higher memory usage, while retaining more Raft entries helps with the availabilities of slow followers: leader is still able to replicate its logs to followers, rather than forcing followers to rebuild its stores from leader snapshots.
Higher `--snapshot-count` holds more Raft entries in memory until snapshot, thus causing [recurrent higher memory usage](https://github.com/kubernetes/kubernetes/issues/60589#issuecomment-371977156). Since leader retains latest Raft entries for longer, a slow follower has more time to catch up before leader snapshot. `--snapshot-count` is a tradeoff between higher memory usage and better availabilities of slow followers.
Since v3.2, the default value of `--snapshot-count` has [changed from from 10,000 to 100,000](https://github.com/coreos/etcd/pull/7160).
#### Change in gRPC dependency (>=3.2.10)