CentOS 5 :: How To Delete NBD Devices

I have created a number of network block devices that I would like to delete, but I have been unable to find any information to do this.

I am using Centos 5.6 and my kernel is 2.6.18-238.el5.

I have been searching the internet for two days now and have noticed some other UNIX systems do have utilities for deleting unwanted devices but nothing for linux.

I created these devices with the vmware supplied PERL script vmware-mount.pl which in turn calls mknod.

The commands would look like:

mknod /dev/nbd0 b 43 0
mknod /dev/nbd1 b 43 1
......

I have tried deleting them from /dev which works temporarily but they come back when I reload the nbd module i.e.

modprobe -r nbd
modprobe nbd

and also if I reboot.

There is a directory tree for each device under /sys/block and I'm guessing this is how /dev is getting repopulated. I cannot remove the directory trees from /sys/block. I get this when I try:

rm: cannot remove `nbd15/queue/iosched/slice_idle': Operation not permitted
rm: cannot remove `nbd15/queue/iosched/slice_async_rq': Operation not permitted
...... there are 25 lines like this ....

When I do a vgsan I see this:Reading all physical volumes. This may take a while...

/dev/nbd0: read failed after 0 of 4096 at 0: Input/output error
/dev/nbd0: read failed after 0 of 4096 at 2199022141440: Input/output error

and in the messages log I see this:

Aug 15 21:04:06 udon-desktop kernel: nbd15: Attempted send on closed socket
Aug 15 21:04:06 udon-desktop kernel: end_request: I/O error, dev nbd15, sector 0