I'd recommend trying it without async I/O just to see where you can get. Filesystemio_options=none Truss Oracle session executing "recover standby database" command shows Oracle waitng IO: 21328/1: kaio(AIOWAIT, 0xFFFFFFFFFFFFFFFF) Err#22 EINVAL 21328/1: kaio(AIOWAIT, 0xFFFFFFFFFFFFFFFF) Err#22 EINVAL 21328/1: kaio(AIOWAIT, 0xFFFFFFFFFFFFFFFF) Err#22 EINVAL -- http://www.freelists.org/webpage/oracle-l