[lug] Interface CRC error on USB connected SATA drive

[Chris Riddoch]

I wish I'd noticed this thread sooner...

There's a program I use called 'hashdeep' which is meant to help you verify
file hashes recursively into directories...

https://github.com/jessek/hashdeep/

If you're just wanting to validate that the metadata is the same, I think
maybe rsync could help with that somehow?

On Sat, Sep 10, 2016 at 7:18 PM, Jed S. Baer <blug at jbaer.cotse.net> wrote:

> On Sat, 10 Sep 2016 13:26:34 -0600
> Lee Woodworth wrote:
>
> > 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.
>
> Yeah, the OS cache can be flushed using fsync. I think we just have
> to trust the HD manufacturer for the drive cache. But I do get the point
> of making sure that I'm reading from what got written to disk, and not
> from any cache.
>
> > 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.
>
> Currently, using uas. I'll make a to-do item to see about changing that.
> I assume I have to do some module blacklisting, and/or some other
> incantations.
>
> > 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.
>
> Well, absent further evidence, I think I'm going to go with what I found
> initially, which is that it's probably some signaling or data on the
> wire, and an intermittent failure maybe from stuffing 167GB through the
> interface as fast as it could be made to go. And that the driver retried
> and it worked.
>
> I believe I have everything fixed now so that errors will get noticed
> if/when they happen too. I guess I sorta understand why a distro would
> not include various "server" type things, such as smart, in a
> desktop-target distribution. But then if things do go wrong, well, I
> guess they just do.
>
> Thank you for the suggestions.
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-- 
Chris Riddoch
http://www.syntacticsugar.org/
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