errors from external USB disk

[Matthias Apitz]

El día Wednesday, February 26, 2014 a las 02:55:27PM +0100, Polytropon escribió:

> On Wed, 26 Feb 2014 13:17:14 +0100, Matthias Apitz wrote:
> > Sometimes, after the dump finished, a re-read of the file to get the MD5
> > checksum results in errors and I was highly concerned about the integrity
> > of my dumps on this device.
> 
> What error? Can you post the error message and the command
> which caused it?

While copying big files from the failing disk to another with 'cp -Rp'
I saw:

Feb 23 18:48:07 La-Habana kernel: (da0:umass-sim0:0:0:0): READ(10). CDB:
28 00 01 cf d9 cf 00 00 0e 00 
Feb 23 18:48:07 La-Habana kernel: (da0:umass-sim0:0:0:0): CAM status:
CCB request completed with an error
Feb 23 18:48:07 La-Habana kernel: (da0:umass-sim0:0:0:0): Retrying command

> > I bought another 2.5 TB disk and was able to copy all the files (around
> > 1TB) over, i.e. the device could now be owerwritte while testing.
> > 
> > What is the best way to run a test on the disk? I'm thinking in
> > something like reading/writing the block in place for many days
> > (it's around 1.5 TB). Any ideas?
> 
> You can start by looking at the S.M.A.R.T. data (sysutils/smartmontools
> and sysutils/smartcontrol), see "man smartctl" for "smartctl -a".
> This should help you to identify possible hardware errors.

I dis this already, but it does not show much:


# smartctl -a /dev/da0 -d scsi
smartctl 6.1 2013-03-16 r3800 [FreeBSD 10.0-CURRENT i386] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke,
www.smartmontools.org

=== START OF INFORMATION SECTION ===
Vendor:               Freecom
Product:              Hard Drive XS
Revision:             1.00
User Capacity:        1,500,301,910,016 bytes [1,50 TB]
Logical block size:   512 bytes
Device type:          disk
Local Time is:        Thu Feb 27 12:55:52 2014 CET
SMART support is:     Available - device has SMART capability.
SMART support is:     Enabled
Temperature Warning:  Disabled or Not Supported

=== START OF READ SMART DATA SECTION ===
SMART Health Status: OK

Error Counter logging not supported

Device does not support Self Test logging

> If the disk is connected to USB, data _could_ be "lost" on that
> way, too. Still it seems that your file system on disk is not
> damaged (check with fsck -f /dev/da1s1a in umounted state).
> 
> The backup file should be entirely readable. You can copy or dd
> it to /dev/null to make sure the entire file is being read.

I always do md5 checksums and store them along with the dumps to be
sure, even after years, that the dump is still what it was, or after
copying the dump to a new place, etc.

Thanks

	matthias

-- 
Matthias Apitz               |  /"\ ASCII Ribbon Campaign: www.asciiribbon.org
E-mail: guru at unixarea.de     |  \ / - No HTML/RTF in E-mail
WWW: http://www.unixarea.de/ |   X  - No proprietary attachments
phone: +49-170-4527211       |  / \ - Respect for open standards