Interesting. http://linux.die.net/man/2/sync http://linux.die.net/man/2/sync says On Linux, sync is guaranteed only to schedule the dirty blocks for Ac

Interesting. http://linux.die.net/man/2/sync http://linux.die.net/man/2/sync says On Linux, sync is guaranteed only to schedule the dirty blocks for According to the standard specification (e.g., POSIX.1-2001), sync() schedules the writes, but may return before the actual writing is done. However, since version 1.3.20 Linux does actually wait. (This still does not guarantee data integrity: modern disks have large caches.) So it seems like the sleep(2) is there to give the disk enough time to write the cache data.