Re: reading errors on JMicron JM20337 USB-SATA

["Lev A. Melnikovsky" <melnikovsky@mail.ru>]

  On Sun, 2 Aug 2009 at 6:03pm, Artur Skawina wrote:

AS> Lev A. Melnikovsky wrote:
AS> > I have read through a year old thread on "JMicron JM20337 USB-SATA data
AS> > corruption bugfix" and it seems here's another aspect of the same
AS> > problem. The SATA disk has genuine errors (bad sectors, just in case: I
AS> > am not going to use it but to recover some data from it). Unfortunately
AS> > when a bad block is read no error is returned, instead a caller is
AS> > blocked indefinitely (until the USB cable is removed). The system log is
AS> > filled with repetitive
AS> > 
AS> > sd 3:0:0:0: [sdf] Sense Key : 0x0 [current]
AS> > sd 3:0:0:0: [sdf] ASC=0x0 ASCQ=0x0
AS> 
AS> yes, jmicron bridges do not report errors properly and just stall pretty
AS> much indefinitely; found out the hard way, when a disk started to develop
My interpretation was different - the bridge firmware does not crash but 
remains alive (it does not report the error properly but "zis iz probably 
perfectly normal behaviour for a Vogon"). This is the Linux kernel that 
indefinitely tries to re-read. Am I wrong?

AS> What did work for my case was to copy the data from the disk and every 
AS> time the process stalled turn off power to the sata drive for a few 
AS> seconds (leaving the bridge connected). The bridge in most cases 
AS> recovered and a bit more data got off the drive.
My nerve is too weak to touch ground/power until the data line is 
disconnected. Running -rc1 seems not so dangerous...

-L