Previous releases of Berkeley DB returned the system error EIO when the memp_fget interface was called to retrieve a page, the page did not exist, and the DB_MPOOL_CREATE flag was not set. In the 3.3 release, the error DB_PAGE_NOTFOUND is returned instead, to allow applications to distinguish between recoverable and non-recoverable errors. Applications calling the memp_fget interface and checking for a return of EIO should check for DB_PAGE_NOTFOUND instead.
Previous releases of Berkeley DB treated filesystem I/O failure (the most common of which the filesystem running out of space), as a fatal error, returning DB_RUNRECOVERY. When a filesystem failure happens in the 3.3 release Berkeley DB returns the underlying system error (usually EIO), but can continue to run. Applications should abort any enclosing transaction when a recoverable system error occurs in order to recover from the error.
Copyright Sleepycat Software