Customer use 5600 V3 connected to a AIX host, which is installed Huawei multipath “ultrapath”. The link between storage and host is normal, then to find a Huawei 16KB Lun mapped on the AIX host : hdisk2.
When create VG by hdisk2, system prompts the error :
Host prompts the error as follows :
To use the storage on the AIX, need to really create a LUN and map it to the host. Before remap the real LUN on the AIX, to remove Command-Device on the host by the following method :
1. Make sure that all the Inband Command status of the store mapping view is Disable：
Method to modify the Command Inband state：
Note: please fill mapping_view_id by actual situation.
2. Make sure that Auto-Scan Switch is Off：
Method to modify the Switch Auto-Scan state：
3. Run cfgmgr -v to scan disk on the AIX, and then delete the disk sign rmdev -dl hdisk2
Use the ultrapath command to query the disk information of hdisk2 :
To show LUN name is LUNV, LUN capacity is 16KB. When product is OceanStor V3 series and OceanStor 18000 series, Command-Device size is 16KB and it is mapped to the host which scans Command-Device as a 16KB size disk. Then it can be concluded that hdisk2 is Command-Device mapped to the host.
The so-called "Command-Device" is the virtual LUN, which is 16KB LUN mapped to the host. Command-Device provides internal communication channels for application servers and storage devices, such as : "host automatically scan function” on storage terminal, “Value-Added business management”on host terminal.
Command-Device is a virtual LUN from storage mapping, and it is not a real storage disk which can’t be used to run real customer service. So when the client in the host to the disk VG hdisk2 creation, the system prompts error.