I can't find anything about this in the docs except[1]. I also can't find any issues in their bug tracker related to clickhouse not using fsync[2].

I can however find code that actually calls fsync[3][4]. To be fair I haven't read enough to determine how this (doesn't) affect durability. Nevertheless I'm wondering do you have a source for this claim?

  [1]: https://clickhouse.yandex/docs/en/operations/settings/settings/#fsync-metadata
  [2]: https://github.com/ClickHouse/ClickHouse/search?q=fsync&type=Issues
  [3]: https://github.com/ClickHouse/ClickHouse/blob/355b1e5594119e036a2d62988bfa42bc8b1a1687/dbms/src/IO/WriteBufferFromFileDescriptor.cpp#L113
  [4]: https://github.com/ClickHouse/ClickHouse/blob/e765733a26cfc4cecc13c981686560338256a6b1/dbms/src/IO/WriteBufferAIO.cpp#L98