Seagate Medalist ST3636A Product Manual page 85

Command Set
In addition to caching, dynamic sparing of bad sectors has been implemented
for cached write commands. This ensures that cached data that has already
been reported as written successfully gets written, even if an error should
occur.
If a sector cannot be written, the drive will dynamically assign an alternate
sector and continue writing the data. If an error occurs during re-allocation, the
drive will drop out of write caching and report the error as an ID Not Found. If
the write command is still active on the AT interface, the error is reported
during that command; otherwise, it is reported on the next command.
Technical Reference Manual
Chapter 7
Page 73