HDIO_GETGEO_BIG_RAW is an ide specific hack introduced in 2.3.99-pre3.
There are no known programs using this ioctl.

Its aim was to provide current CHS translation to the user-space,
but very often it provides what driver thinks is a current translation
(drive with LBA have to support only one physical translation, also
 drive may not support chosen translation and there is no return value check).

hdparm -I can be used instead, it provides correct information
(and bogus data is still accessible through /proc/ide/hdX/geometry).