Otherwise, coordinator may not react to changing stats after explicit
calls to trigger_load_stats_refresh() done on node replace or table
creation, if stats take longer to refresh than it takes the
coordinator to go idle.
The periodic refresh does wake up the topology coordinator, so the
issue is not dramatic in production, but it's annoying in tests, which
take longer because of that.
Fixes#25163
Refreshing stats will signal _topo_sm.event, so do it before waiting
for the event, to avoiding busy looping in the coordinator.
This will produce lots of logs in test cases which enable debug-level
logging in the raft logger.
Refs #28086
Checking for work is not atomic, so there is room for missed
notification. Especially that notifications are not always triggered
from fibers which take the group0 guard.
Fix by subscribing for the event before checking for work.
Fixes#27958
We switched to the size-based load balancing, which now has more
strict requirements for load stats. We no longer need only per-node
stats (capacity), but also per-tablet stats.
Bootstrapping a node triggers stats refresh, but allocating tablets on
table creation didn't. So after creating a table, load balancer
couldn't make progress for up to 60s (stats refresh period).
This makes tests take longer, and can even cause failures if tests are
using a low-enough timeout.
Fixes#27921
Stats refresh will be triggered on topology coordinator by events like
allocating new tablets on table creation. For refresh to be effective,
all replicas must see the new tablets, otherwise stats will be
incomplete.
If a test tries to move a tablet, it assumes the tablets are stable.
This fixes flakiness exposed by size-based load-balancing and a later
change to refresh stats sooner.
It's a global operation, so we can use any server.
It's not only convenient. The call via api.disable_tablet_balancing()
confuse people to think that it's a per-server operation. This leads
to proliferation of code which does it needlessly on all servers.
This will move responsibility for running tests with pytest in the same manner as it was done with boost tests. From this commit, test.py is not responsible anymore for running python tests and relies completely on pytest.
This is another step for unification of test execution.
Convert skip_mode function to `pytest.mark` to be able to use to annotate the whole module instead of each test explicitly.
NOTE: this is a breaking change. From this commit, several directories with tests will require a path to the file to launch the test. Affected directories
test/alternator
test/broadcast_tables
test/cql
test/cqlpy
test/rest_api
Changes only in framework, so no backport.
This PR will increase the amount of the tests by 30 test, due to the fact that how test.py and pytest discover tests. test.py count a file as a test, and when skip used in suite.yaml it will exclude the tests from discovery completely.
While the pytest count test funstion as a test and uses skip_mode mark and will discover the tests, but it will skip them during execution, hence the difference
test.py output before PR:
```bash
> ./test.py --mode=release rest_api/test_compaction_task rest_api/test_task_manager --list --no-gather-metrics
```
test.py output in this PR:
```bash
> ./test.py --mode=release test/rest_api/test_compaction_task.py test/rest_api/test_task_manager.py --list
rest_api/test_compaction_task.py::test_global_major_keyspace_compaction_task.release.1
rest_api/test_compaction_task.py::test_major_keyspace_compaction_task.release.1
rest_api/test_compaction_task.py::test_cleanup_keyspace_compaction_task.release.1
rest_api/test_compaction_task.py::test_offstrategy_keyspace_compaction_task.release.1
rest_api/test_compaction_task.py::test_rewrite_sstables_keyspace_compaction_task.release.1
rest_api/test_compaction_task.py::test_reshaping_compaction_task.release.1
rest_api/test_compaction_task.py::test_resharding_compaction_task.release.1
rest_api/test_compaction_task.py::test_regular_compaction_task.release.1
rest_api/test_compaction_task.py::test_compaction_task_abort.release.1
rest_api/test_compaction_task.py::test_major_keyspace_compaction_task_async.release.1
rest_api/test_compaction_task.py::test_cleanup_keyspace_compaction_task_async.release.1
rest_api/test_compaction_task.py::test_offstrategy_keyspace_compaction_task_async.release.1
rest_api/test_compaction_task.py::test_rewrite_sstables_keyspace_compaction_task_async.release.1
rest_api/test_compaction_task.py::test_compaction_progress[major_keyspace_compaction_task_impl_run_fail].release.1
rest_api/test_compaction_task.py::test_compaction_progress[shard_major_keyspace_compaction_task_impl_run_fail].release.1
rest_api/test_compaction_task.py::test_compaction_progress[table_major_keyspace_compaction_task_impl_run_fail].release.1
rest_api/test_task_manager.py::test_task_manager_modules.release.1
rest_api/test_task_manager.py::test_task_manager_tasks.release.1
rest_api/test_task_manager.py::test_task_manager_status_running.release.1
rest_api/test_task_manager.py::test_task_manager_status_done.release.1
rest_api/test_task_manager.py::test_task_manager_status_failed.release.1
rest_api/test_task_manager.py::test_task_manager_not_abortable.release.1
rest_api/test_task_manager.py::test_task_manager_wait.release.1
rest_api/test_task_manager.py::test_task_manager_ttl.release.1
rest_api/test_task_manager.py::test_task_manager_user_ttl.release.1
rest_api/test_task_manager.py::test_task_manager_sequence_number.release.1
rest_api/test_task_manager.py::test_task_manager_recursive_status.release.1
rest_api/test_task_manager.py::test_module_not_exists.release.1
rest_api/test_task_manager.py::test_task_folding.release.1
rest_api/test_task_manager.py::test_abort_on_unregistered_task.release.1
```
Fixes: https://github.com/scylladb/scylladb/issues/27716Closesscylladb/scylladb#26395
* github.com:scylladb/scylladb:
test.py: fix test_vector_similarity.py
docs: add directories excluded from test.py
test.py: prevent file descriptors leaking
test.py: capture print inside the test
test.py: do not print header for collection with test.py
test.py: remove not supported functionality
test.py: switch of execution of several test directories by test.py runner
test.py: integrate python tests to be executed with pytest runner
test.py: fix test/vector_search_validator to be able to run with pytest
test.py: prepare base class for migration
test.py: move environment preparation to one method
test.py: introduce new environment variable TESTPY_PREPARED_ENVIRONMENT
repair: Implement auto repair for tablet repair
This patch implements the basic auto repair support for tablet repair.
It was decided to add no per table configuration for the initial
implementation, so two scylla yaml config options are introduced to set
the default auto repair configs for all the tablet tables.
- auto_repair_enabled_default
Set true to enable auto repair for tablet tables by default. The value
will be overridden by the per keyspace or per table configuration which
is not implemented yet.
- auto_repair_threshold_default_in_seconds
Set the default time in seconds for the auto repair threshold for tablet
tables. If the time since last repair is bigger than the configured
time, the tablet is eligible for auto repair. The value will be
overridden by the per keyspace or per table configuration which is not
implemented yet.
The following metrcis are added:
- auto_repair_needs_repair_nr
The number of tablets with auto repair enabled that needs repair
- auto_repair_enabled_nr
The number of tablets with auto repair enabled
The metrics are useful to tell if auto repair is falling behind.
In the future, more auto repair scheduling will be added, e.g.,
scheduling based on the repaired and unrepaired sstable set size,
tombstone ratio and so on, in addition to the time based scheduling.
Fixes SCYLLADB-99
New feature. No backport.
Closesscylladb/scylladb#27534
* github.com:scylladb/scylladb:
topology_coordinator: Add metrics for tablet repair
repair: Implement auto repair for tablet repair
This PR:
- Replaces a fixed version name with the variable for the current version in the instructions for installing a non-default version with Web Installer. This will make using the installer more user-friendly.
- Removes the instruction for Open Source from the Web Installer docs.
Fixes https://github.com/scylladb/scylladb/issues/28005
Fixes https://github.com/scylladb/scylladb/issues/28079Closesscylladb/scylladb#28046
* github.com:scylladb/scylladb:
doc: remove the instruction for Open Source from the Web Installer docs
doc: add the version variable to the Web Installer instructions
- scylla_tablet_ops_failed
Number of failed tablet {auto, user} repair
- scylla_tablet_ops_succeeded
Number of succeeded tablet {auto, user} repair
Currently auto_repair and user_repair tablet task are added. We can add
more tablet tasks later, e.g., rebuild, migration.
Create and drop view operations are currently performed on all shards, and their execution is not fully serialized. On slower processors this can lead to interleavings that leave stale entries in `system.scylla_views_build`
A problematic sequence looks like this:
* `on_create_view()` runs on shard 0 → entries for shard 0 and shard 1 are created
* `on_drop_view()` runs on shard 0 → entry for shard 0 is removed
* `on_create_view()` runs on shard 1 → entries for shard 0 and shard 1 are created again
* `on_drop_view()` runs on shard 1 → entry for shard 1 is removed, while the shard 0 entry remains
This results in a leftover row in `system.scylla_views_builds_in_progress`, causing `view_build_test.cc` to get stuck indefinitely in an eventual state and eventually be terminated by CI.
This patch fixes the issue by fully serializing all view create and drop operations through shard 0. Shard 0 becomes the single execution point and notifies other shards to perform their work in order. Requests originating.
new process:
- view_builder::on_create_view(...) runs only on shard 0 and kicks off dispatch_create_view(...) in the background.
- dispatch_create_view(...) (shard 0) first checks should_ignore_tablet_keyspace(...) and returns early if needed.
- dispatch_create_view(...) calls handle_seed_view_build_progress(...) on shard 0. That:
- writes the global “build progress” row across all shards via _sys_ks.register_view_for_building_for_all_shards(...).
- After seeding, dispatch_create_view(...) broadcasts to all shards with container().invoke_on_all(...).
- Each shard runs handle_create_view_local(...), which:
- waits for pending base writes/streams, flushes the base,
- resets the reader to the current token and adds the new view,
- handles errors and triggers _build_step to continue processing.
Drop view
- view_builder::on_drop_view(...) runs only on shard 0 and kicks off dispatch_drop_view(...) in the background.
- dispatch_drop_view(...) (shard 0) first checks should_ignore_tablet_keyspace(...) and returns early if needed.
- It broadcasts handle_drop_view_local(...) to all shards with invoke_on_all(...).
- Each shard runs handle_drop_view_local(...), which:
- removes the view from local build state (_base_to_build_step and _built_views) by scanning existing steps,
- ignores missing keyspace cases.
- After all shards finish local cleanup, shard 0 runs handle_drop_view_global_cleanup(...), which:
- removes global build progress, built‑view state, and view build status in system tables,
Shutdown
- drain() waits on _view_notification_sem before _sem so in‑flight dispatches finish before bookkeeping is halted.
In addition, the test is adjusted to remove the long eventual wait (596.52s / 30 iterations) and instead rely on the default wait of 17 iterations (~4.37 minutes), eliminating unnecessary delays while preserving correctness.
Fixes: https://github.com/scylladb/scylladb/issues/27898
Backport: not required as the problem happens on master
Closesscylladb/scylladb#27929
To prepare for implementation of filtering we skip validation
of where clauses in vector search queries. All queries that would
be blocked by the lack of ALLOW FILTERING now will pass through.
Fixes: VECTOR-410
Closesscylladb/scylladb#27758
We can run Alternator's tests against DynamoDB with `test/alternator/run --aws`, and our intention is that all except a few specially marked should pass on DynamoDB - indicating that the test itself is correct and checks compatibility with DynamoDB and not with some misunderstood spec.
Before this patch series, almost two dozen Alternator's tests failed on DynamoDB. This series fixes most of them.
Refs #26079 (it fixes almost all the problems but probably not all of them so let's keep the issue open for a while longer)
Closesscylladb/scylladb#27995
* github.com:scylladb/scylladb:
test/alternator: fix some expected error messages to fit DynamoDB
test/alternator: fix compressed request test on non-us-east1
test/alternator: fix test's expected error message on DynamoDB
test/alternator: mark Alternator-only test scylla_only
test/alternator: fix test on DynamoDB
test/alternator: increase wait_for_gsi() timeout
test/alternator: fix test passing a spurious parameter
These tools are deprecated and no longer shipped by ScyllaDB packages.
They no longer support the latest SSTable versions and ScyllaDB-only
features, like encryption and dictionary based compression.
Remove them from the documentation.
Closesscylladb/scylladb#27608
The interface of Jenkins has changed, and the instructions for creating
a token are out-of-date. This commit updates them.
Closesscylladb/scylladb#28054
There is a known limitation of the xdist.
Since it makes discovery in each thread, then compare it with master thread. The discovered lists of test should be the same. Sets are not order guaranteed, so they should not be used for parametrized testing, because discovery of the tests with using xdist will fail.
This PR just converts set to dist, to eliminate issue mentioned above.
Unused imports, unused variables and such.
Initially, there were no functional changes, just to get rid of some standard CodeQL warnings.
I've then broken the CI, as apparently there's a install time(!?) Python script creation for the sole purpose of product
naming. I changed it - we have it in etcdir, as SCYLLA-PRODUCT-FILE.
So added (copied from a different script) a get_product() helper function in scylla_util.py and used it instead.
While at it, also fixed the too broad import from scylla_util, which 'forced' me to also fix other specific imports (such as shutil).
Improvement - no need to backport.
Signed-off-by: Yaniv Kaul <yaniv.kaul@scylladb.com>
Closesscylladb/scylladb#27883
We currently do it only for a bootstrapping node, which is a bug. The
missing IP can cause an internal error, for example, in the following
scenario:
- replace fails during streaming,
- all live nodes are shut down before the rollback of replace completes,
- all live nodes are restarted,
- live nodes start hitting internal error in all operations that
require IP of the replacing node (like client requests or REST API
requests coming from nodetool).
We fix the bug here, but we do it separately for replace with different
IP and replace with the same IP.
For replace with different IP, we persist the IP -> host ID mapping
in `system.peers` just like for bootstrap. That's necessary, since there
is no other way to determine IP of the replacing node on restart.
For replace with the same IP, we can't do the same. This would require
deleting the row corresponding to the node being replaced from
`system.peers`. That's fine in theory, as that node is permanently
banned, so its IP shouldn't be needed. Unfortunately, we have many
places in the code where we assume that IP of a topology member is always
present in the address map or that a topology member is always present in
the gossiper endpoint set. Examples of such places:
- nodetool operations,
- REST API endpoints,
- `db::hints::manager::store_hint`,
- `group0_voter_handler::update_nodes`.
We could fix all those places and verify that drivers work properly when
they see a node in the token metadata, but not in `system.peers`.
However, that would be too risky to backport.
We take a different approach. We recover IP of the replacing node on
restart based on the state of the topology state machine and
`system.peers` just after loading `system.peers`.
We rely on the fact that group 0 is set up at this point. The only case
where this assumption is incorrect is a restart in the Raft-based
recovery procedure. However, hitting this problem then seems improbable,
and even if it happens, we can restart the node again after ensuring
that no client and REST API requests come before replace is rolled back
on the new topology coordinator. Hence, it's not worth to complicate the
fix (by e.g. looking at the persistent topology state instead of the
in-memory state machine).
Fixes#28057
Backport this PR to all branches as it fixes a problematic bug.
Closesscylladb/scylladb#27435
* github.com:scylladb/scylladb:
gossiper: add_saved_endpoint: make generations of excluded nodes negative
test: introduce test_full_shutdown_during_replace
utils: error_injection: allow aborting wait_for_message
raft topology: preserve IP -> ID mapping of a replacing node on restart
Fixes#27992
When doing a commit log oversized allocation, we lock out all other writers by grabbing
the _request_controller semaphore fully (max capacity).
We thereafter assert that the semaphore is in fact zero. However, due to how things work
with the bookkeep here, the semaphore can in fact become negative (some paths will not
actually wait for the semaphore, because this could deadlock).
Thus, if, after we grab the semaphore and execution actually returns to us (task schedule),
new_buffer via segment::allocate is called (due to a non-fully-full segment), we might
in fact grab the segment overhead from zero, resulting in a negative semaphore.
The same problem applies later when we try to sanity check the return of our permits.
Fix is trivial, just accept less-than-zero values, and take same possible ltz-value
into account in exit check (returning units)
Added whitebox (special callback interface for sync) unit test that provokes/creates
the race condition explicitly (and reliably).
Closesscylladb/scylladb#27998
The current code:
```
try:
cql.execute(f"INSERT INTO {cf} (pk, t) VALUES (-1, 'x')", host=host[0], execution_profile=cl_one_profile).result()
except Exception:
pass
```
contains a typo: `host=host[0]` which throws an exception becase Host
object is not subscriptable. The test does not fail because the except
block is too broad and suppresses all exceptions.
Fixing the typo alone is insufficient. The write still succeeds because
the remaining nodes are UP and the query uses CL=ONE, so no failure
should be expected.
Another source of flakiness is data verification:
```
SELECT * FROM {cf} WHERE pk = 0;
```
Even when a coordinator is explicitly provided, using CL=ONE does not
guarantee a local read. The coordinator may forward the read request to
another replica, causing the verification to fail nondeterministically.
This patch rewrites the tests to address these issues:
- Fix the typo: `host[0]` to `hosts[0]`
- Verify data using `MUTATION_FRAGMENTS({cf})` which guarantees a local
read on the coordinator node
- Reconnect the driver after node restart
Fixes https://github.com/scylladb/scylladb/issues/27933Closesscylladb/scylladb#27934
With migration to the pytest, file descriptors will be hanged during the whole life of the process. Previously it was not an issue, because test.py was executing only one file with Popen, so descriptors will be freed with process done. With new approach they are blocked. This will allow to eliminate this.
Fix issue when we had issue with getting cluster and then trying to set it dirty while it None.
Put cluster to the pool only if it was created
In the current state pytest do not support the order of execution, so this parameter is removed. There is no big need in this due to the differences what pytest and test.py counted test. pytest run test functions in the threads, while test.py executed test files in the threads. That's why pytest's way is more granular and allows to fill threads better.
Remove skip node, since it already added as a pytest mark for each test in the file.
Remove pool_size, since this is not used by pytest at all. Pytest uses
xdist to set the amount of threads instead of pool_size used by test.py
With this commit test.py will lose ability to run tests by itself always bypassing execution to the pytest.
NOTE: this is a breaking change. From this commit, several directories
with tests will require a path to the file to launch the test.
Affected directories
test/alternator
test/broadcast_tables
test/cql
test/cqlpy
test/rest_api
With this commit test.py will be bypassing the tests execution to the pytest. However, it will still be able to run test by itself.
With providing test name like `broadcast_tables/test_broadcast_tables` it will execute test with test.py runner, but if the path to the file will be provided like `test/broadcast_tables/test_broadcast_tables.py` it will bypass execution to the pytest.
`--test-py-init` tells to run pytest session in test.py-compatible mode
Update the help text for the name parameter for test.py about changes
how it works and which directory is served by pytest
build_mode fixture have dynamic scope. It depends how the pytest is
executed. When it executed through test.py scope will be session and
since it's broader that package everything work fine. While with pure
pytest it will fail because build_mode will have module scope.
This fix allows to run tests with pure pytest, this needed for migration
test to be executed by pytest runner instead test.py.
Since all tests share the same base class and some of the tests executed by test.py and some with pytest, we need to handle two cases where configuration is located: suite.yaml and test_config.yaml
After full migration suite.yaml case will be removed
Since anyway these two methods should be called one by one in two different cases: when test.py executes test and pytest executes test, merging them into one. Additionally, set environment variable to show the underneath pytest process that environment was already prepared and there is no need to clean directories or start additional services.
Introduce the new environment variable that will be used to signalize to the pytest runner that environment war already prepared by test.py. This needed to be able to run the test with pytest and test.py(that actually will run pytest underneath).
This patch implements the basic auto repair support for tablet repair.
It was decided to add no per table configuration for the initial
implementation, so two scylla yaml config options are introduced to set
the default auto repair configs for all the tablet tables.
- auto_repair_enabled_default
Set true to enable auto repair for tablet tables by default. The value
will be overridden by the per keyspace or per table configuration which
is not implemented yet.
- auto_repair_threshold_default_in_seconds
Set the default time in seconds for the auto repair threshold for tablet
tables. If the time since last repair is bigger than the configured
time, the tablet is eligible for auto repair. The value will be
overridden by the per keyspace or per table configuration which is not
implemented yet.
The following metrcis are added:
- auto_repair_needs_repair_nr
The number of tablets with auto repair enabled that needs repair
- auto_repair_enabled_nr
The number of tablets with auto repair enabled
The metrics are useful to tell if auto repair is falling behind.
In the future, more auto repair scheduling will be added, e.g.,
scheduling based on the repaired and unrepaired sstable set size,
tombstone ratio and so on, in addition to the time based scheduling.
Fixes SCYLLADB-99
Allow creating materialized views and secondary indexes in a tablets keyspace only if it's RF-rack-valid, and enforce RF-rack-validity while the keyspace has views by restricting some operations:
* Altering a keyspace's RF if it would make the keyspace RF-rack-invalid
* Adding a node in a new rack
* Removing / Decommissioning the last node in a rack
Previously the config option `rf_rack_valid_keyspaces` was required for creating views. We now remove this restriction - it's not needed because we always maintain RF-rack-validity for keyspaces with views.
The restrictions are relevant only for keyspaces with numerical RF. Keyspace with rack-list-based RF are always RF-rack-valid.
Fixesscylladb/scylladb#23345
Fixes https://github.com/scylladb/scylladb/issues/26820
backport to relevant versions for materialized views with tablets since it depends on rf-rack validity
Closesscylladb/scylladb#26354
* github.com:scylladb/scylladb:
docs: update RF-rack restrictions
cql3: don't apply RF-rack restrictions on vector indexes
cql3: add warning when creating mv/index with tablets about rf-rack
service/tablet_allocator: always allow tablet merge of tables with views
locator: extend rf-rack validation for rack lists
test: test rf-rack validity when creating keyspace during node ops
locator: fix rf-rack validation during node join/remove
test: test topology restrictions for views with tablets
test: add test_topology_ops_with_rf_rack_valid
topology coordinator: restrict node join/remove to preserve RF-rack validity
topology coordinator: add validation to node remove
locator: extend rf-rack validation functions
view: change validate_view_keyspace to allow MVs if RF=Racks
db: enforce rf-rack-validity for keyspaces with views
replica/db: add enforce_rf_rack_validity_for_keyspace helper
db: remove enforce parameter from check_rf_rack_validity
test: adjust test to not break rf-rack validity
Disabling of balancing waits for topology state machine to become idle, to guarantee that no migrations are happening or will happen after the call returns. But it doesn't interrupt the scheduler, which means the call can take arbitrary amount of time. It may wait for tablet repair to be finished, which can take many hours.
We should do it via topology request, which will interrupt the tablet scheduler.
Enabling of balancing can be immediate.
Fixes https://github.com/scylladb/scylladb/issues/27647Fixes#27210Closesscylladb/scylladb#27736
* https://github.com/scylladb/scylladb:
test: Verify that repair doesn't block disabling of tablet load balancing
tablets: Make balancing disabling call preempt tablet transitions
VECTOR_SEARCH_INDEXING permission didn't work on cdc tables as we mistakenly checked for vector indexes on the cdc table insted of the base.
This patch fixes that and adds a test that validates this behavior.
Fixes: VECTOR-476
Closesscylladb/scylladb#28050
Call discover_staging_sstables in view_update_generator::start() instead
of in the constructor, because the constructor is called during
initialization before sstables are loaded.
The initialization order was changed in 5d1f74b86a and caused this
regression. It means the view update generator won't discover staging
sstables on startup and view updates won't be generated for them. It
also causes issues in sstable cleanup.
view_update_generator::start() is called in a later stage of the
initialization, after sstable loading, so do the discovery of staging
sstables there.
Fixesscylladb/scylladb#27956Closesscylladb/scylladb#27970
Currently, database::truncate_table_on_all_shards calls the table::can_flush only on the coordinator shard
and therefore it may miss shards with dirty data if the coordinator shard happens to have empty memtables, leading to clearing the memtables with dirty data rather than flushing them.
This change fixes that by making flush safe to be called, even if the memtable list is empty, and calling it on every shard that can flush (i.e. seal_immediate_fn is engaged).
Also, change database_test::do_with_some_data is use random keys instead of hard-coded key names, to reproduce this issue with `snapshot_list_contains_dropped_tables`.
Fixes#27639
* The issue exists since forever and might cause data loss due to wrongly clearing the memtable, so it needs backport to all live versions
Closesscylladb/scylladb#27643
* github.com:scylladb/scylladb:
test: database_test: do_with_some_data: randomize keys
database: truncate_table_on_all_shards: drop outdated TODO comment
database: truncate_table_on_all_shards: consider can_flush on all shards
memtable_list: unify can_flush and may_flush
test: database_test: add test_flush_empty_table_waits_on_outstanding_flush
replica: table, storage_group, compaction_group: add needs_flush
test: database_test: do_with_some_data_in_thread: accept void callback function
2-DC cluster parallel non-RBNO rebuild failure when expanding RF in DC2.
Steps to reproduce:
1. Provision a cluster with 2 datacenters and at least 2 nodes in the second datacenter.
2. Let’s assume datacenter names are "dc1" and "dc2".
3. Create a keyspace ("keyspace1") with RF=0 in dc2.
4. Populate some data into dc1.
5. Change keyspace1 replication in dc2 to 2.
6. On 2 nodes in dc2 run the following command in parallel:
nodetool rebuild --source-dc dc1
Parallel execution of rebuilds is not possible with RBNO enabled.
This test is the repro for #27804Closesscylladb/scylladb#27747
