mirror of
https://github.com/tendermint/tendermint.git
synced 2026-01-08 06:15:33 +00:00
7b3138e694
* spec: update spec with tendermint updates - this in preperation of deleting the spec folder in docs in tendermint/tendermint Signed-off-by: Marko Baricevic <marbar3778@yahoo.com> * spec: added in reactors & p2p Signed-off-by: Marko Baricevic <marbar3778@yahoo.com> * spec: update readme in spec to comply with docs site Signed-off-by: Marko Baricevic <marbar3778@yahoo.com> * docs: addded more changes from tednermint/tendermint Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>
33 lines
1.4 KiB
Markdown
33 lines
1.4 KiB
Markdown
# WAL
|
||
|
||
Consensus module writes every message to the WAL (write-ahead log).
|
||
|
||
It also issues fsync syscall through
|
||
[File#Sync](https://golang.org/pkg/os/#File.Sync) for messages signed by this
|
||
node (to prevent double signing).
|
||
|
||
Under the hood, it uses
|
||
[autofile.Group](https://godoc.org/github.com/tendermint/tmlibs/autofile#Group),
|
||
which rotates files when those get too big (> 10MB).
|
||
|
||
The total maximum size is 1GB. We only need the latest block and the block before it,
|
||
but if the former is dragging on across many rounds, we want all those rounds.
|
||
|
||
## Replay
|
||
|
||
Consensus module will replay all the messages of the last height written to WAL
|
||
before a crash (if such occurs).
|
||
|
||
The private validator may try to sign messages during replay because it runs
|
||
somewhat autonomously and does not know about replay process.
|
||
|
||
For example, if we got all the way to precommit in the WAL and then crash,
|
||
after we replay the proposal message, the private validator will try to sign a
|
||
prevote. But it will fail. That's ok because we’ll see the prevote later in the
|
||
WAL. Then it will go to precommit, and that time it will work because the
|
||
private validator contains the `LastSignBytes` and then we’ll replay the
|
||
precommit from the WAL.
|
||
|
||
Make sure to read about [WAL corruption](https://github.com/tendermint/tendermint/blob/master/docs/tendermint-core/running-in-production.md#wal-corruption)
|
||
and recovery strategies.
|