On 06/30/2014 11:48 AM, Andras Horvath wrote:
> Hi Everyone,
>
> I've been having an issue for a month or so now that I seem unable to track down.
>
> I have an external USB drive for backup. When I start copying from the computer to the external disk, it starts to fail sooner or later. Whether at a large file or after several small ones, but it fails dropping messages like this (taken from dmesg):
>
> ...
>
>
> I tested the disk on 2 different computers (one of them is brand new server, the other is old one serving for years) in 3 different USB covers (they're new ones too) with 2 different brand new disks. The disks are 2 TB in size (a bit less actually, around 1.8 TB formatted).

When the errors occur, can you tell if the drive spins down and then 
back up?

If so, I have seen similar errors with a pair of bus-powered 2.5 inch 
1TB Seagate USB3 drives; it seems like the drives actually draw more 
power than the port can deliver for an extended amount of time.  I have 
to put them on a USB 2 port instead of a USB 3 port to get them to be 
reliable for writing (reading seems to never be the problem).  You 
didn't say if the drives were USB-powered or not, but the port spinning 
the drives down would be the first thing I would check.

As to Debian 6 being able to work with it and SL6 not, that could be a 
kernel difference where the Debian kernel is waiting and retrying longer 
in the case where the drive is spinning down.

If the drive is not bus-powered, it could still be spinning down due to 
its green features, and maybe the Debian 6 USB stack is disabling those 
features (or at least not complaining about those features) whereas the 
SL6 kernel is not as forgiving of drives spinning down or isn't 
disabling those features.