[phs2501]

Linux kernel aio will often still block when dealing with the page cache even if you request nonblocking. The workaround for this is to use O_DIRECT, which is okay for databases that do their own cache management but not for something like nginx (which is depending on the OS cache).

Glibc's posix aio (aio_*(3)), on the other hand, does not use Linux's kernel aio AFAIK. It probably uses thread pools. It also uses signals to signal completion. It is not generally considered performant.

[dschiptsov]

Yes, good points about caching, Informix does everything by itself, indeed, on raw devices or direct mapped files, which is the only way to maintain not evenrual, but strong data consistency Thanks for clarifying.