Some one used AUL utility to recover millions of LOB values, and told me the recovery was very slow, about 10MB generated per minute. I don't think so, and I want to tell him it's impossible slow. They may choose the wrong method to estimate the recovery speed. There are two storage modes of the LOB values. First mode is inline storage, store the LOB value with other columns value, the second mode is file storage, store each LOB value in a distinct file.
Inline is the default method (SET LOB_STORAGE 0), so all the LOB value is stored in one file, the file increase should be very fast. When I try to unload the SYS.SOURCE$ table, the speed is usually 6-8MB per second on my notebook. So this is impossible.
Under file storage mode (SET LOB_STORAGE 1), each LOB value will be stored in distinct file (LOB_xxxxxxxx_xxxx.dat), and the relative LOB column will record the LOB file name. In this mode, the file increase speed maybe slow for the text file which stores the table data, and 10MB per minute is reasonable. When you estimate the recovery speed, you should take the LOB files into account. Or you just count the rows of the text file contains the table data (BLOB Recovery Example).
If AUL give you such a bad impression, it's really unlucky, for me not a big issue, but for you, it's critical because you are not choosing the right recovery methods, and spend a lot of time in doing nothing. On a Linux platform based Intel x86 CPUs, it will run very fast.