[lug] Interface CRC error on USB connected SATA drive

[Lee Woodworth]

On 09/10/2016 11:49 AM, Jed S. Baer wrote:
> On Fri, 9 Sep 2016 22:27:40 -0600
> Lee Woodworth wrote:
> 
>> I would vote for a driver retry of a command that didn't
>> complete within the driver's deadline. That said, I would
>> still want to know why the command failed or was slow. Dmesg
>> is where I would start looking for driver error messages.
> 
> I'm not seeing anything in dmesg, but maybe too much time elapsed. I will
> keep an eye out for that.
> 
>> A full diff after a complete cache flush would test for corruption
>> and somewhat exercise the drives. Completley powering off the external
>> drive would be a start for the cache flush. Then a smart short
>> test might show something abnormal.
> 
> I did do a smart long test. No problems indicated. The md5sum operation
> suggested by Davide should provide some good drive exercise as well.
> 
> I think cache auto-flushes after a certain amount of time.

There are two cache levels I am thinking about, the OS buffer cache and
the drive cache. Somebody that knows more than me could tell you for sure,
but I think modified buffer-cache pages get written to the target backing
store but do not immediately get erased/released. Unmodified pages get
overwritten as needed. E.g. vmstat shows 431MB in the buffer cache of file
server here after 6 hours of minimal activity. Drive cache policy is hardware
dependent which is why I use a power-off when possible to ensure its empty.

Since you are using a themaltake dock, it is possible you are using the uas
driver even if it is USB 2. I would see if there is a uas directory in
somewhere /sys and whether it has a device symlink/directory.

Looks like your errors are not simple ones to diagnose. Maybe A/B testing
using the same USB port+cable for the dock vs. another known good external
enclosure would tell you whether the dock is the issue.

> _______________________________________________
> Web Page:  http://lug.boulder.co.us
> Mailing List: http://lists.lug.boulder.co.us/mailman/listinfo/lug
> Join us on IRC: irc.hackingsociety.org port=6667 channel=#hackingsociety
>