Everything worked properly until this time, but today i have this problem:
in MD Storage Manager i cannot to see nothing. If i try with automatic dicovery i have:
found 0 host(s).
The controller and led is working properly
In EventViewer i have this only error:
"Message from SM agent service: SMagent: The SMagent service attempted to start but terminated. Possible causes include:  The access virtual disk is disabled in NVSRAM.  No RAID controller modules with compatible firmware were found.  The default logical unit number (LUN) assigned to the access virtual disk (typically 7 or 31) is not in the range supported by the host or is already in use by the host for another device. See your storage management documentation for more details."
Did you assign IP addresses to the MD3000? If so, assuming you have them plugged into your network, try adding an array manually and point it to the 2 IP addresses. This can be done from any system in your network (not just the server).
If you didn't set IPs, you may need to call Dell support as it sounds like you may have accidentally removed the host mapping for lun 31, which means you can no longer manage/monitor the unit via the SAS connection.
In Windows device manager look under "disk drives" and check to see if you have "Universal X-Port" device. This is the access Lun 31 from the storage array. If you unmapped this device in the MDSM application then the inband management will no longer work.
I recommend plugging the network ports from both of the raid controllers into your network, remove any arrays discovered in MDSM, and then try and discover the array. By default the raid controllers will try and pick up a DHCP address, if no DHCP they default to 192.168.128.101 for controller 0 and 192.168.128.102 for controller. If the array is found, check to see if there is a Lun 31 mapped to the host name under the virtual disk mappings. If lun 31 is not mapped go to the configure tab, then host-to-virtualdisk-mapping select the Access lun, choose 31 for the lun number and map it to the host. If this all works go to device manager and rescan and you should see the universal x-port. Restart the Modular disk storage manager service. Go back to MDSM and ADD the inband management specifying the IP of the host.
If none of the above works then I recommend calling Dell Tech support.