[ale] USB "duplicate" drive issue on CentOS

[Edward Holcroft]

All,

I am running USB HDD backups (encrypted with LUKS) on multiple CentOS 7
boxes using rsync. The drives get swapped out for each day of the week and
I use autofs to mount them. On some (not all) of these servers I encounter
an issue whereby the drive does not automount and shows has a duplicate
entry in messages:

Jun 16 10:48:01 atlfs systemd: Device
dev-disk-by\x2duuid-0a647b12\x2dfce7\x2d4745\x2db6f7\x2d8bfa3ffd56d8.device
appeared twice with different sysfs paths
/sys/devices/pci0000:00/0000:00:02.0/0000:04:00.0/0000:05:00.0/0000:06:00.0/usb2/2-2/2-2:1.0/host5/target5:0:0/5:0:0:0/block/sdd
and
/sys/devices/pci0000:00/0000:00:02.0/0000:04:00.0/0000:05:00.0/0000:06:00.0/usb2/2-2/2-2:1.0/host92/target92:0:0/92:0:0:0/block/sdi

​The FIRST time ​I put the USB backup drive (say MONDAY) in place, it all
works fine, but the following week when I put that same drive in again, and
any subsequent time, this error comes up.

If I reboot the server, the error goes away ... until the next week. So
somehow, it seems that device is being retained by the system and then
shows as a duplicate the next time the drive is connected to the USB dock.

It works fine on some machines and failing on others. Same hardware, same
version of ​CentOS. Same setup. On a working machine I get the following
when plugging in USB drives:

Jun 16 08:14:44 nwofs systemd: Expecting device /dev/mapper/THURSDAY...
Jun 16 08:14:44 nwofs systemd: Starting Cryptography Setup for THURSDAY...
Jun 16 08:14:47 nwofs systemd: Found device /dev/mapper/THURSDAY.
Jun 16 08:14:47 nwofs systemd: Started Cryptography Setup for THURSDAY.

and lsblk shows:

sdf               8:80   0  1.8T  0 disk
└─THURSDAY      253:7    0  1.8T  0 crypt

On a failing machine I get the error in messages about the device appearing
twice and the following output from lsblk showing no drive available until
I open it manually:

sdg                          8:96   0  1.8T  0 disk


If I try to manually delete the path to the offending duplicate block
device (e.g.
/sys/devices/pci0000:00/0000:00:02.0/0000:04:00.0/0000:05:00.0/0000:06:00.0/usb2/2-2/2-2:1.0/host5/target5:0:0/5:0:0:0/block/sdd),
I get "No such file or directory".

So for now I have been doing manual backups on the non-working servers.
Doh! I thought I would easily find the issue by comparing
working/non-working. Alas, this is not to be.

Any ideas?

​ed​

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