Udev can it change USB disk mapping on it's own ?

ls -l /dev/disk/by-uuid/
total 0
lrwxrwxrwx 1 root root 10 Feb  8  2011 2c29259c-81c5-4784-a67b-2e33065063bb -> ../../sda3
lrwxrwxrwx 1 root root 10 Feb  8  2011 4C07-A6DC -> ../../sda4
lrwxrwxrwx 1 root root 10 Aug 12 11:32 86ec805a-cde8-4347-9f3b-ff4ab3b203cc -> ../../sdb1
lrwxrwxrwx 1 root root 10 Feb  8  2011 92625f6a-b38e-4809-b647-f7eff9d3d310 -> ../../sda2

Ok so the USB disk device name changed from sde1 to sdb1. Is that possible without a reboot ? As far as I know the disk was plugged in all the time and I’m sure there was no reboot.

Is it possible to make permanent udev rules for such a disk ? I believe it is but could someone point me to some simple howto ?

Thanks a lot in advance.

Best regards,
Greg

I don’t know.
The following commands provide some infos about the device though:

/sbin/udevadm info -q all -n /dev/sdb
/sbin/udevadm info -a -p $(/sbin/udevadm info -q path -n /dev/sdb)

And this shows the udev rules it reads:

/sbin/udevadm test /dev/sdb

The rule could look like this (trying to change the node name based on serail short ID), but this one doesn’t work:

ACTION!="add|change", GOTO="usb_devname_end"
SUBSYSTEM!="block", GOTO="usb_devname_end"
KERNEL=="loop*|ram*", GOTO="usb_devname_end"
ENV{ID_SERIAL_SHORT}=="6E664FFFFFFF", NAME="sde"
LABEL="usb_devname_end"

You can try different things. I don’t know if it’s possible.

Thanks for help. I have discovered that the name was changed because the disk has external power supply and there was a power supply outage. That’s why the name was changed.

Best regards,
Greg