On Thursday, May 2, 2002, at 12:13 AM, Entwicklung wrote:
Regarding 'bad blocks' - I haven't really marked any 'bad blocks' until now and am not too sure I know how it is done... will have to read up on that.
You create one or more records in the Extents Overflow B-tree for file ID 5 (kHFSBadBlockFileID), fork 0 (i.e. the data fork). Since there is no entry for the bad blocks "file" in either the MDB or catalog, the first record would have its startBlock set to 0 (i.e. offset of 0 blocks into the "file"). If you need other discontiguous bad block extents, you would create additional records.
Any idea what happens if I don't mark the blocks of the embedded volume as 'bad blocks' but just mark them as allocated in the allocation bitmap of the HFS-Wrapper ? Could this be a potential cause of any problems ?
It might confuse older disk repair utilities that only see the wrapper, or are trying to repair the wrapper as a plain HFS volume. For read-only media, it probably isn't a serious problem. For writable media, you would run the risk of having such a utility "repair" the bitmap by unsetting the bits for the embedded volume, and potentially overwriting part of the embedded volume when writing to the wrapper.
-Mark