ATA READ command timeout (and worse)

[Jaw-Shiang Joshua Huang]

Stephen McKay <smckay at internode.on.net> said: 
> On Tuesday, 17th June 2003, Jaw-Shiang Joshua Huang wrote:
> 
> >Do you think it's possible that sometimes the disk is not working properly?
> >In my memory, the disk DMA limitation checks the ATA identify command report
> >from the HDD or the register of IDE controller.  I'll doubt the HDD first. :)
> 
> What do you mean by "not working properly"?  The disks are initially probed
> with their correct speeds (and the cables are correct too).  One of the
> disks then appears to be using the wrong cable after recovery from the
> timeouts.  I can't see how that could be anything other than a driver bug.
> 

I just think that your disk might have some strange behavior after reading or writing some bad sectors.  I have added some log code in the FreeBSD ata driver to record the physical blkno of the timeout bp.  In my experience, this kind of timeout always hits specific blkno of the disk.  Then anything might happen, such as the machine halted when resetting the ata channel, disable DMA and falling into PIO mode, reading no device info from the channel register and remove the configuration of HDD, or ...  Even in windows, an buggy HDD also makes it freeze.

I also believe that there should be some bug in the ata driver to handle the error scenario.  But it is also possible that the IDE controller cannot handle the error condition, either.  The ata driver will be buggy when the IDE controller cannot work properly with a dangling disk.  

I perfer that it's a h/w problem(IDE controller or HDD) because the ATA driver in FreeBSD has a simple logic when your disk does not support tag queueing or what else.

> >Also, I guess that 230W is not enough to provide the current for 4 disks
> >concurrently.  Can you try your experiment with only 3 disks connected power
> >line again?  If possible, two will be better.
> 
> This seems like a good idea.  I'll do this when I get back to testing.
> 
> >Sorry that I did not provide you any suggest but only questions.  I have
> >not had a SiI IDE controller, either.
> 
> I'm sure someone, somewhere, is using them. :-)
> 
> Stephen.

I like your postive point.  :)

Joshua, Taiwan.


--
Regards, 

Joshua Huang  --  joshuah at synology.com
Tel: 886-2-25521814 ext. 823
Synology Inc.