* Initialize cluster version at wall-clock time
Previously, new clusters would begin at version 0. After this change,
clusters will initialize at a version matching wall-clock time. Instead
of using the Unix epoch (or Windows epoch), FDB clusters will use a new
epoch, defaulting to January 1, 2010, 01:00:00+00:00. In the future,
this base epoch will be modifiable through fdbcli, allowing
administrators to advance the cluster version.
Basing the version off of time allows different FDB clusters to share
data without running into version issues.
* Send version epoch to master
* Cleanup
* Update fdbserver/storageserver.actor.cpp
Co-authored-by: A.J. Beamon <aj.beamon@snowflake.com>
* Jump directly to expected version if possible
* Fix initial version issue on storage servers
* Add random recovery offset to start version in simulation
* Type fixes
* Disable reference time by default
Enable on a cluster using the fdbcli command `versionepoch add 0`.
* Use correct recoveryTransactionVersion when recovering
* Allow version epoch to be adjusted forwards (to decrease the version)
* Set version epoch in simulation
* Add quiet database check to ensure small version offset
* Fix initial version issue on storage servers
* Disable reference time by default
Enable on a cluster using the fdbcli command `versionepoch add 0`.
* Add fdbcli command to read/write version epoch
* Cause recovery when version epoch is set
* Handle optional version epoch key
* Add ability to clear the version epoch
This causes version advancement to revert to the old methodology whereas
versions attempt to advance by about a million versions per second,
instead of trying to match the clock.
* Update transaction access
* Modify version epoch to use microseconds instead of seconds
* Modify fdbcli version target API
Move commands from `versionepoch` to `targetversion` top level command.
* Add fdbcli tests for
* Temporarily disable targetversion cli tests
* Fix version epoch fetch issue
* Fix Arena issue
* Reduce max version jump in simulation to 1,000,000
* Rework fdbcli API
It now requires two commands to fully switch a cluster to using the
version epoch. First, enable the version epoch with `versionepoch
enable` or `versionepoch set <versionepoch>`. At this point, versions
will be given out at a faster or slower rate in an attempt to reach the
expected version. Then, run `versionepoch commit` to perform a one time
jump to the expected version. This is essentially irreversible.
* Temporarily disable old targetversion tests
* Cleanup
* Move version epoch buggify to sequencer
This will cause some issues with the QuietDatabase check for the version
offset - namely, it won't do anything, since the version epoch is not
being written to the txnStateStore in simulation. This will get fixed in
the future.
Co-authored-by: A.J. Beamon <aj.beamon@snowflake.com>
* Revert "Revert "Refactor: ClusterController driving cluster-recovery state machine""
Major changes includes:
1. Re-revert Sequencer refactor commits listed below (in listed order):
1.a. This reverts commit bb17e194d9.
1.b. This reverts commit d174bb2e06.
1.c. This reverts commit 30b05b469c.
2. Update Status.actor to track ClusterController interface to track
recovery status.
3. Introduce a ServerKnob to define "cluster recovery trace event"
prefix; for now keeping it as "Master", however, it should allow
smooth transition to "Cluster" prefix as it seems more appropriate.
At present, cluster recovery process consists of following steps:
1. ClusterController clusterWatchDatabase actor recruits
master/sequencer process.
2. Sequencer process implements the cluster recovery state machine,
responsible to recruit all other processes as well restore the
cluster state.
Patch proposes a scheme where the cluster recovery state machine
is implemented and driven by the ClusterController process instead
of the Sequencer process.
Advantages of the scheme could be:
1. Simplified design where ClusterController recruits "sequencer"
process like other worker processes compared to current scheme
where "sequencer" process gets special treatment. In newer scheme
sequencer is responsible for maintaining/providing
"committed version" (as expected).
2. ClusterController is responsible for worker processes recruitment,
the sequencer though orchestrating the recovery state machine, it
need to reachout to the ClusterController for recruiting worker
processes etc.
NOTE:
Patch has moved the recovery state machine code from
'sequencer' -> 'cluster-controller' process, however, necessary
updates were done for both functionality as well as performance
improvement reasons.
Next Steps:
Cluster recovery documentation will be updated in near future.
- Only report commit version when commit version is larger than the known committed version.
- Fix task priorities of [Get/Report]LiveCommittedVersion [request/reply].
- Fix some code style issues.
For backup workers working on old epochs, once their work is done, they will
notify the master. Then the master removes them from the log system and
acknowledge back to the backup workers so that they can gracefully shut down.
The popping of a backup worker is stalled if there are workers from older
epochs still working. Otherwise, workers from old epochs will lost data.
However, allowing newer epoch to start backup can cause holes in version ranges.
The restore process must verify the backup progress to make sure there are no
holes, otherwise it has to wait.
Ray Jenkins