On tuesday on of our server ran in to the problem described in the blog entry below.
http://nsrd.info/blog/2013/04/08/debugging-device-daemons-on-a-storage-node/
A restart of the services made the devices usable again.
Maybe there is a connection with the setting “Dynamic nsrmmds” which I enabled some days before?
I don’t think it’s connected to dynamic nsrmmd’s; I don’t use them on the lab server that encountered the problem.