On Sat, 9 Feb 2002, Sergiy Kudryk wrote:
With Windows Direct CD 5.0 (2.54) i dont' have any problem. I use several new Verbatim CDRW discs. Under Linux i always see errors "Ignoring read error on sector" :-( .
If pktcdvd found error on disc he simply skip copying data into that sector ?
This error message happens when the kernel asks the packet driver to write an incomplete packet. In that case the driver first has to read the missing part of the packet from the disc, and then write the whole packet back to disc. If the read fails, this error message is printed, and the packet driver has two choices, both bad: 1. It could skip copying data to the disc. 2. It could copy the new data to the disc, even though it doesn't know how to preserve the old data. (because reading the old data failed.) The packet driver currently chooses the second alternative, but that's not the problem. It would be equally bad to choose the first alternative. The real mystery is why the read fails. I have seen some drives reporting "device not ready, long write in progress" when you send them a read request while they are writing a packet. However, the packet writing patch includes modifications in the scsi layer to handle this case and retry the read request until it succeeds. If you are using an ide cdrw without scsi emulation, this retry logic is not being used, but with scsi emulation (which I think you are using) it is used. Maybe the read requests can fail for other reasons that are not detected by the scsi layer retry logic? I don't know yet.
Another thing you could try is to make the read speed equal to the write speed. Your drive/disc combination seemed to be able to handle 8x, so you could use this patch. (I have no idea if this will really help.)
Thanks but i can't apply this patch to pktcdvd.c - too many rejected strings:
This is probably because you have already changed the argument to pkt_adjust_speed manually, as I suggested previously. Just make sure that this value is not larger than the maximum write speed supported by your drive/disc. -- Peter Osterlund - petero2@telia.com http://w1.894.telia.com/~u89404340