OceanStor 5600 V3 When the customer finds a mapping of 16KB LUN in AIX, to create VG is failure

Publication Date:  2015-06-21 Views:  401 Downloads:  11
Issue Description

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 :

Alarm Information

Host prompts the error as follows :

Handling Process

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

Root Cause

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.

Solution

参见处理过程中所用的解决方案

Suggestions
This issue is mostly due to that there is no correct understanding of the functional characteristics in particular or more complex application scenarios. It causes the results that the expected results are not consistent with real. The suggestion for processing the similar problems is to have identification with whether the use of product features is appropriate by the product manual.

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