In scale-out storage, the erasure code (EC) mechanism provides good redundancy protection for data. Which of the following statements are false about the EC mechanism? (Choose all that apply.)

• A. In node-level security scenarios, if the number of storage nodes after capacity expansion is greater than or equal to N + M, the system will automatically unfold N + M:1 to N + M in the background.
• B. During capacity expansion, if the current disk pool supports a higher EC redundancy ratio, the value of N can be increased for the disk pool after services are stopped.
• C. In node-level security scenarios, if the number of storage nodes is greater than or equal to N + M, an N + M redundancy ratio is used. If the number of storage nodes is greater than or equal to (N
  + M)/M and less than N + M, an N + M:1 redundancy ratio is used.
• D. The node-level security layout has the highest space utilization, the disks on a faulty node can be taken over by a normal node, and the fault impact scope is smaller.

A financial customer purchased an OceanStor Dorado 18000 series storage system for basic service deployment. During management, an engineer discovered that the running status of an iSCSI port on DeviceManager was "Link down". After checking the indicator in the equipment room, the engineer discovered that the link indicator of the iSCSI front-end port was steady red.
Which of the following are not possible causes of the exception?

• A. The optical module type is incompatible with the host port.
• B. The IP address of the service network port on the application server is incorrectly set.
• C. The cable between the application server and the storage device is loose.
• D. The IP address of the iSCSI front-end port is incorrect.

Assume a financial customer purchased a Huawei all-flash storage device for service deployment. During routine usage of the storage device, the administrator found that the storage device performance fluctuated greatly and checked the performance issue. Which of the following is not a performance fluctuation check item?

• A. Whether SmartKit runs abnormally at the time when performance fluctuates
• B. Whether the hit rate changes abruptly at the time when performance fluctuates
• C. Whether there are obvious hardware resource bottlenecks on the storage device at the time when performance fluctuates
• D. Whether obvious storage background tasks (such as data reconstruction) are ongoing at the time when performance fluctuates

Which statements are true about hardware installation of Huawei OceanStor Pacific series storage systems? (Choose all that apply.)

• A. When powering on devices, engineers must power on the devices in the cabinet and then the cabinet.
• B. Before connecting node signal cables, internal components, PGND cables, and power cables must be installed.
• C. Optical modules are electrostatic sensitive components. When operating the devices, engineers must wear electrostatic discharge (ESD) wrist straps. There is no specific requirement for wearing ESD gloves and clothes.
• D. The procedure for cabinet non-fastening installation on a concrete floor is the same as that on an ESD floor, including positioning, leveling, combining, and securing cabinets.

When learning the SmartVirtualization feature of Huawei flash storage, a new employee is not familiar with eDevLUNs and external LUNs. Which of the following statements are true about the eDevLUNs and external LUNs? (Choose all that apply.)

• A. eDevLUNs belong to storage pools created in the local storage system.
• B. eDevLUNs can be created regardless of whether external LUNs are normal.
• C. An eDevLUN consists of actual data and metadata. The storage space required by metadata is provided by the heterogeneous storage system, and the physical space required by actual data is provided by the local storage system.
• D. If the administrator has not configured any value-added feature for eDevLUNs, each eDevLUN occupies small space in the storage pool of the local storage system.