02.12.2010 07:11, Greg KH ÐÐÑÐÑ: > On Thu, Dec 02, 2010 at 03:40:40AM +0300, Linux User wrote: > >> >From time to time I experience problems with external hard drives >> connected via USB bus to my laptop. An USB device may suddenly go >> off-line after receiving some amount of data. >> > Are you sure this isn't an electrical issue? The log shows that the > device is electrically disconnecting itself, which is not something that > the kernel can do. > Actually, external drives' behavior is more complex and there are about three ways a failure may happen and self-disconnecting of a device is only one of manifestations of the problem. 1) The transfer rate is unexpectedly appears to be as low as 3..6Mb/s instead of normal 20-30Mb/s with continuous resets of the device every minute or less (reported in system log), same for reading or writing, but nothing happens when the disk is idle. After n'th reset the device may disconnect itself. The SATA hard disks themself is healthy and totally OK, there are no problems when either of them is connected to desktop PC via (e)SATA-SATA cable. 2) The transfer rate is normal, no problems during idle operation or reading but few resets may happen less frequently, after n'th (n is 3..5, anyway < 10) reset the device goes off-line and kernel reports failure to commit to filesystem journal. After that the device may go on-line again but filesystem may be already corrupted. 3) After (1) or (2) happens, disconnecting the USB cable and putting it back may result in error messages telling that the device cannot be attached to the system (see pieces of log in the attachment). > If you use a different cable does this go away? How about providing > more power to the drive with an external power supply I think that power supply is OK. Those sudden disconnects only look like problems with power supply, but just the same device works without any problems with just the same power supply when attached via (e)SATA-SATA interface. --- Linux User
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usb_failure_messages.tar.gz
Description: GNU Zip compressed data
