Re: Filesystem errors on armv7 -current

On Oct 22, 2026, at 6:35 AM, bob prohaska <fbsd@www.zefox.net> wrote:
> 
> On Wed, Oct 21, 2026 at 10:32:07PM -0700, Bakul Shah wrote:
>> 
>> One can buy a cheap inline USB power meter or tester to see
>> what sort of voltage/current is in use. Fancier ones such as
>> FNIRSI FNB48P that will let you see a realtime graph of
>> voltage/current at various sampling rates + you can upload
>> this data (+ there is vibe coded s/w to run on linux/mac for
>> this as well). Very useful for debugging this sort of
>> problems.
> 
> I have chopped a USB cable to bring out the power leads and
> connected them to a voltmeter in the past. That would seem
> adequate to identify a faulty power supply. I haven't tried
> it in this specific case, but  given the absence of messages
> from umass other than those at boot, is there any point?

The boot umass messages were fine.

The problem is you are dealing with potentially marginal
devices that may misbehave under load and no guarantee that
software or firmware will catch such errors. By default the
pi2b  limits total current (across all 4 USB ports) to 600
mA.  You can add 'max_usb_current=1' to config.txt to
increase it to 1.2A (IIRC) - provided Pi's power supply is
capable.  [Some earlier HDD USB disks came up with weird USB
cables for plugging into *two* ports to get enough power!]

It may be that the problem you're seeing is software related
but such USB measurements can clearly eliminate power as an
issue.