Disappearing USB drives

[Brian]

I guess posting here is a long shot in view of the amount of traffic
in the group, but what's to lose?

I'm trying to find the solution to USB drives 'disappearing' while
being accessed. I'm doing a backup (via sudo!) with a number of
recursive copy operations, and suddenly the copy will report that the
target filesystem is read-only, and then a few attempted copies after
that, the files will disappear, and it appears that the mount point
has no drive mounted there if an ls -a is run, but df still lists the
drive in its output.

The drives affected are THREE different external USB drives, two
Western Digital 8TB drives and a smaller Seagate 2TB driver which has
been mounted in an external USB enclosure.

The cure to the problem is simple. Either dismount and remount the
drive, which fixes it immediately, or wait about 20-30 minutes, when
the problem fixes itself spontaneously, the files reappear and the
drive goes back to write access.

The good folks in the Ubuntu hardware group are baffled (I'm running
the latest Ubuntu-based Linux Mint, V19.3, on an AMD Phenom x2
six-core desktop). Is there anybody left here with any ideas?

Brian.

[Joe Beanfish]

Post by Brian
I guess posting here is a long shot in view of the amount of traffic
in the group, but what's to lose?
I'm trying to find the solution to USB drives 'disappearing' while
being accessed. I'm doing a backup (via sudo!) with a number of
recursive copy operations, and suddenly the copy will report that the
target filesystem is read-only, and then a few attempted copies after
that, the files will disappear, and it appears that the mount point
has no drive mounted there if an ls -a is run, but df still lists the
drive in its output.
The drives affected are THREE different external USB drives, two
Western Digital 8TB drives and a smaller Seagate 2TB driver which has
been mounted in an external USB enclosure.
The cure to the problem is simple. Either dismount and remount the
drive, which fixes it immediately, or wait about 20-30 minutes, when
the problem fixes itself spontaneously, the files reappear and the
drive goes back to write access.
The good folks in the Ubuntu hardware group are baffled (I'm running
the latest Ubuntu-based Linux Mint, V19.3, on an AMD Phenom x2
six-core desktop). Is there anybody left here with any ideas?
Brian.

Flaky USB port?
Not enough power on the port (if you're not using external power
for the drives)?

[Henrik Carlqvist]

Post by Joe Beanfish

Post by Brian
I'm trying to find the solution to USB drives 'disappearing' while
being accessed.

Flaky USB port?
Not enough power on the port (if you're not using external power for the
drives)?

Both very possible causes. The best way to find clues about what is
happening is probably to study the output of the command "dmesg".

regards Henrik

[Mike]

Post by Joe Beanfish

Post by Brian
report that the
target filesystem is read-only, and then a few attempted copies after
that, the files will disappear, and it appears that the mount point
has no drive mounted there if an ls -a is run, but df still lists the
drive in its output.

Flaky USB port?
Not enough power on the port (if you're not using external power
for the drives)?

Not enough reliable power from the *external* power supply if you *are*
using one :)

Having had an external USB/network NAS with a switchmode powerbrick
slowly go out of spec, such that the drive would work ok until you wrote
wrote wrote wrote wrote at it, and then it would suddenly decide to
spin down/up the drive and get confused ...

Can you hear what the drive is doing? Can you see the activity light
misbehaving (unusual loss of activity, or active light coming on
FULL and staying on ... )

Filesystems going read-only is often a defence mechanism when other
things are going wrong, so it's a symptom (not a cause).

Definitely check the output of dmesg (or /var/log/messages or syslog)
from the point where you connected the drive, until the failure happens.

[Jeff Jonas]

Post by Brian
I'm trying to find the solution to USB drives 'disappearing'
while being accessed.
The drives affected are THREE different external USB drives,
two Western Digital 8TB drives
and a smaller Seagate 2TB drive

If the problem is happening while writing,
check the log with 'dmesg' for USB or drive errors.
That's the best clue for what's triggering the cascade of problems.

If the drive goes offline after being idle for 1/2 hour,
the drive is going into "power save mode",
something Linux knows nothing about.
My workaround was to put the drive on a Windows system
and using the mfgr's utility to set power-save to "never"
so the drive stays spinning.

-- jeffj
--

[Carlos E.R.]

Post by Jeff Jonas

Post by Brian
I'm trying to find the solution to USB drives 'disappearing'
while being accessed.
The drives affected are THREE different external USB drives,
two Western Digital 8TB drives
and a smaller Seagate 2TB drive

If the problem is happening while writing,
check the log with 'dmesg' for USB or drive errors.
That's the best clue for what's triggering the cascade of problems.
If the drive goes offline after being idle for 1/2 hour,
the drive is going into "power save mode",
something Linux knows nothing about.
My workaround was to put the drive on a Windows system
and using the mfgr's utility to set power-save to "never"
so the drive stays spinning.

man hdparm