[plug] RPi USB drive backups

[Chris Hoy Poy]

Hi Chris,

Remounting the drive read only is a standard error handling process for a
disk experiencing certain errors

The smartctl test is performed by the drive itself, good news : it's
probably not the drive, however I've had drives that were clearly failing
happily do these tests (probably an issue on their connector etc)

USB cables are pretty notorious for being flakey etc
Have had them work with some drives and not others, total pita

Rsync over a large volume , particularly with lots of small files and
directories, is a pretty brutal stress test of several subsystems.

/Chris

On Thu, 20 Mar 2025, 10:26 am Chris McCormick, <chris at mccormick.cx> wrote:

> Hi,
>
> Thanks for your reply.
>
> smartctl seems to think the hardware is fine. I did smartctl -a and it
> reported nothing unusual. I also ran a self test and this was the result:
>
> $ sudo smartctl -l selftest /dev/sdb
> smartctl 7.2 2020-12-30 r5155 [aarch64-linux-6.1.21-v8+] (local build)
> Copyright (C) 2002-20, Bruce Allen, Christian Franke,
> www.smartmontools.org
>
> === START OF READ SMART DATA SECTION ===
> SMART Self-test log structure revision number 1
> Num  Test_Description    Status                  Remaining
> LifeTime(hours)  LBA_of_first_error
> # 1  Short offline       Completed without error       00%      6625
>      -
>
> If the drive or the USB hub was overheating would that cause IO errors?
> I should also mention that the OS seems to remount the drive a read only
> once this happens.
>
> Chris.
>
>
> On 20/03/2025 08:09, Chris Hoy Poy wrote:
> > Hi Chris
> >
> > If it's timing out with IO errors, you probably have a hardware problem
> > somewhere in the mix.
> >
> > Cable , connector, hub or USB hard drive (probably the destination drive
> > by the sounds of it).
> >
> > Shouldn't matter which software you use to copy (dd, rsync etc) - though
> > very different technical processes, if it's dropping data somewhere then
> > they will bomb out.
> >
> > Cheers
> > /Chris
> >
> >
> > On Thu, 20 Mar 2025, 8:03 am Chris McCormick, <chris at mccormick.cx
> > <mailto:chris at mccormick.cx>> wrote:
> >
> >     Hey all,
> >
> >     Unfortunately I couldn't make it to the recent RPi meetup, otherwise
> >     that would have been a good place to ask about this.
> >
> >     Anyway, I have an RPi with a powered USB hub and two USB hard drives
> >     plugged in doing backups. The second drive is a mirror of the first
> >     which I have traditionally done with rsync. I recently replaced one
> of
> >     the drives and I now need to mirror the full drive to the new drive.
> >     I've been using rsync to do this but it takes ages just to do the
> >     initial diff and craps out after a while with IO errors and unmounts
> >     the
> >     destination drive. The total size of data is 2.3Tb.
> >
> >     What is a good way to do a fast copy of all of the data on one USB
> >     drive
> >     to the other? I'd prefer not to have to stuff around with partitions
> if
> >     possible as they have slightly different partitions on each drive and
> >     different labels etc.
> >
> >     LLMs were no help at all with this so I'm relying on the PLUG brains
> >     trust! 😅 Thanks for any suggestions.
> >
> >     Chris.
> >
> >     --
> >     https://mccormick.cx/ <https://mccormick.cx/>
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>
> --
> https://mccormick.cx/
>
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