[filimonov]

Two tables whose custom disks sit on one backing disk fail to attach at server start: Cannot open file …/clickhouse_access_check_<server uuid> or Can't unlink file clickhouse_access_check_… (FILE_DOESNT_EXIST) While checking access for disk …. Every disk probes its access with that one file name, and since #2573 custom disks are created outside storage_policies_mutex, so the probes of two disks over the same store overwrite and unlink each other's file. A process-wide mutex around the probe in IDisk::checkAccess; config disks are created one after another anyway, so nothing else changes.

Seen on the 26.8 port #2805 in test_filesystem_cache (tables test and test_size_in_name, cache disks over hdd_blob, server log at 12:15:44: three probes on hdd_blob within 1 ms, two fail on unlink; https://altinity-build-artifacts.s3.amazonaws.com/PRs/2805/a2147e556977e195b2d117c61b61d1274e080436/integration_tests_amd_asan_ubsan_db_disk_old_analyzer_5_8/job.log). antalya-26.6 carries 2573 since 2026-11-04; its integration suite has no test_cache_file_size_in_name, so the race has not shown in its CI.

Testing

• New unit test DiskAccessCheck.ProbesOfDisksOverOneDirectoryDoNotOverlap (src/Disks/tests/gtest_disk_access_check.cpp): two disks over one directory, started in parallel; the probe of the second must wait for the first. Fails before the fix (two probes at once), passes after, 20/20 repeats.
• Release unit_tests_dbms --gtest_filter='CAS*' on this branch: 2822 passed, 0 failed, 2 disabled.

Related: #2573
Related: #2805

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Tables on custom disks that share a backing disk no longer fail to load at server start with FILE_DOESNT_EXIST on clickhouse_access_check_<server uuid>: the disk access probes are serialized.

Documentation entry for user-facing changes

• No documentation needed.

CI/CD Options

Exclude tests:

• Fast test
• Integration Tests
• Stateless tests
• Stateful tests
• Unit tests
• Performance tests
• Aarch64 tests
• All with ASAN
• All with TSAN
• All with MSAN
• All with UBSAN
• All with Coverage
• All Regression
• Disable CI Cache

Regression jobs to run:

• Fast suites (mostly <1h)
• Aggregate Functions (2h)
• Alter (1.5h)
• Benchmark (30m)
• CAS (content-addressed storage; Antalya only)
• ClickHouse Keeper (1h)
• Iceberg (2h)
• LDAP (1h)
• OAuth (5m)
• Parquet (1.5h)
• RBAC (1.5h)
• SSL Server (1h)
• S3 (2h)
• S3 Export (2h)
• Swarms (30m)
• Tiered Storage (2h)

[github-actions]

Workflow [PR], commit [bb9bf73]