In this case, the 2 nodes are not yet added since the setConf entry must have index > 10 so that it cannot be committed. If the original Leader goes down, the setConf cannot succeed.
Tsz-Wo On Mon, Aug 22, 2022 at 7:35 PM Asad Awadia <[email protected]> wrote: > > > "If the group has 3 nodes, then the log entries in the leader A are not > yet committed since the entries 7-10 have not replicated to a majority" > > Entries 7-10 are committed because the group started with just 1 node which > had majority of 1 > > Aftet that 2 blank nodes were added > > On Mon., Aug. 22, 2022, 10:27 p.m. Tsz Wo Sze, <[email protected]> wrote: >> >> Hi Asad, >> >> If the group has 3 nodes, then the log entries in the leader A are not >> yet committed since the entries 7-10 have not replicated to a majority >> of nodes. The entries 7-10 can be either committed later or safely >> thrown away: >> >> - If A becomes the leader again, it will resend the entries 7-10 to >> the followers. >> >> - Suppose 2 nodes B and C have voted a new leader among themselves. >> The new leader, say B, will first record a new log entry 7' for >> starting a new term and send it to C. Once C has received 7', the >> entry becomes committed. When A rejoins the group, A must truncate >> its log and throw away entries 7-10. >> >> Hope it helps. >> Tsz-Wo >> >> On Mon, Aug 22, 2022 at 2:04 PM Asad Awadia <[email protected]> wrote: >> > >> > Hello, >> > >> > What happens if the leader goes down while the follower nodes are still >> > catching up (like after just starting up) >> > >> > Eg >> > 1 node is the leader and has logs from 0-10 >> > 2 nodes join and start replicating the log >> > After the 2 follower nodes get to log index 6 >> > The leader goes down >> > What happens to the log entries from 7-10? >> > Are they thrown away? Now the new leader will overwrite?
