Messages in this thread |  | | Date | Thu, 19 Dec 1996 16:46:28 +0300 (IST) | From | Gadi Oxman <> | Subject | Re: hdb: DSC timeout - what's that ? |
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On Thu, 19 Dec 1996, Pierfrancesco Caci wrote:
> After being able to compile 2.1.16, I now get this error message at > boot time and also when accessing the cdrom after a long delay: > > hdc: DSC timeout > > /dev/hdb is the cdrom drive. Never had problems with it so far. > > There's no reference in /usr/src/linux/Documentation/cdrom/ide.txt to > this kind of error message. Or at least I didn't see it :-) > > The drive appears to work correctly though. Should I worry about > something ? > > Pf
This is a non fatal error - more of a debugging message.
New IDE hardware is starting to provide equivalents to the SCSI disconnect/reconnect features. As of 2.1.15, the IDE driver will attempt to overlap CDROM seek operations with operations on the other IDE device which shares the same interface.
Two new messages are possible:
1. disabled DSC seek overlap
This happens when the driver reached the conclusion that the CDROM is "cheating" and doesn't really support overlapped operation.
2. DSC timeout - this happens when the CDROM appears to properly disconnect on a seek operation, but the seek operation seems to be taking a lot of time to complete.
A flood of "DSC timeout" messages indicates a problem and will decrease performance, but if we see them only once in a while as above, it looks like everything is fine and we should simply increase the timeout a bit.
In any case, none of those messages is fatal. Overlapping is used to improve performance, but when problems are detected, we will repeat the operation in a non overlapped fashion.
Gadi
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