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Parts Replacement 12

OceanStor 18500 V3 and 18800 V3 Mission Critical Storage System V300R003

This document describes the procedure for replacing the parts of storage system in terms of safety operations, preparations, and precautions.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).




asynchronous remote replication

A kind of remote replication. When the data on the primary site is updated, the data does not need to be updated on the mirroring site synchronously to finish the update. In this way, performance is not reduced due to data mirroring.





A periodic operation performed on the data stored in the database for the purposes of database recovery in case that the database is faulty. The backup also refers to data synchronization between active and standby boards.

back-end disk port

The port that is used to transfer data between the controller and disks.


A range of transmission frequencies that a transmission line or channel can carry in a network. In fact, it is the difference between the highest and lowest frequencies the transmission line or channel. The greater the bandwidth, the faster the data transfer rate.

baud rate

The maximum rate of signal state changes per second on a communications circuit. In low-speed communications, each signal state corresponds to a code bit, then the baud rate and the bit rate are the same, that is, the reciprocal of code bits in one second.

bit error

An incompatibility between a bit in a transmitted digital signal and the corresponding bit in the received digital signal.




cache hit ratio

The ratio of directly accessed I/O from cache to all I/O during a read task.

cache prefetch strategy

According to the operation in which data has been read or is being read, the required data is read from a disk into the cache in advance.

captive screw

After the screw is loosened, screw caps and bolts are not disconnected from the main body.


A snapshot technology. The source data is completely copied to generate a data duplicate; therefore the duplicate needs the storage space as the same size as the source data. It is also called clone. In the VIS system, it is also called third-mirror break-off snapshot.


A mechanism adopted to improve the system performance. Several devices of the same type form a cluster. The exterior of a cluster is some like a kind of equipment. In the interior of a cluster, the nodes share the load.


A technology for ensuring data security and integrity in a storage system. It is used to store the mission-critical data of the system.

coffer disk

Disks that build up the coffer.

command device

A special LUN through which the host can send inband commands to storage devices.

constant prefetch

A cache prefetch strategy. The size of the data to be prefetched is the size as set. This strategy applies to the applications that require reading data of a fixed size in a certain order. An example is the streaming media demanded by multiple subscribers who use the same bit rate.




data switch

A data switch used for interconnections between controllers.

dirty data

The data that is stored temporarily on cache and has not been written onto disks.

disk enclosure

A enclosure that consists of components such as expansion modules, disk modules, power supplies, and fan modules. Storage capacity of a storage system can be expanded by adding more disk enclosures to the system.

disk utilization

The percentage of used capacity in the total available capacity.





Two controllers in one enclosure are called Engine.

external storage system

Disk arrays of different forms, especially disk arrays from different vendors.




fan module

The module that consists of fans and fan boards and dissipates heat for the system.

free disk

A disk that is not used in a storage system.





A device that connects two network segments using different protocols. It is used to translate the data in the two network segments.




inband management

Inband management means that the management control information of the network and the carrier service information of the user network are transferred through the same logical channel. Inband management enables users to manage storage arrays through commands. Management commands are sent through service channels, that is, I/O write and read channels. The advantages of inband management include high speed, stable transfer, and no additional management network ports required.

intelligent prefetch

A cache prefetch strategy. The system software calculates a proper size of prefetched data. This strategy applies to a read application involving a single bit stream or to the situations where you do not know whether the data is read in a certain order. An example is reading or writing a file.




load balance

A method of adjusting the system, application components and data to averagely distribute the applied I/O or computing requests for physical resources of the system.




management interface module

The module that integrates one or more management network ports.

management network

An entity that provides a means to transmit and process the information related to network management.

management network port

The network port on the controller enclosure that is connected to the maintenance terminal. It is provided for the remote maintenance terminal. Its IP address can be modified with the change of customers' environment.

member disk

A disk in a redundant array of inexpensive disks (RAID) group.





A managed device in the network. For a device with a single frame, one node stands for one device. For a device with multiple frames, one node stands for one frame of the device.




out-of-band management

A management mode used during out-of-band networking. In the out-of-band management mode, the management and control information of the network and the bearer service information of the user network are transmitted through different logical channels.

overload protection

The protection measures for devices in case that the overloaded main power lines cause damage to the protector as results of overheat, overvoltage, and overcurrent.




power failure protection

When the external power failure occurs, the AC PEM depends on the battery for power supply, which ensures the integrity of the dirty data in cache.


When the system monitors that a member disk in a RAID group is to fail, the system copies the data on the disk to a hot spare disk in advance. This technology is called pre-copy.

primary network port

The service network port that is in use.

prior controller

In the multipathing environment, the owning controller of the AS LUN that corresponds to the LUN on the storage array is called the prior controller of the AS LUN.





The process of restoring the data saved on a faulty member disk in a RAID group.

remote replication

A core technology for disaster recovery and a foundation that implements remote data synchronization and disaster recovery. This technology remotely maintains a set of data mirror through the remote data connection function of the storage devices that are separated in different places. Even when a disaster occurs, the data backup on the remote storage device is not affected. Remote replication can be divided into synchronous remote replication and asynchronous remote replication by whether the host that requires mirrors needs the confirmation information of the remote replication site.




service data

The user and/or network information required for the normal functioning of services.

service processor

A component that provides a system management and control platform, including power modules and fan modules.

SFP optical transceiver

A component that can make data conversion between optical signals and electrical signals and that can receive and transfer data.

single point of failure

A type of failure. Data transmission over a network is stopped and cannot be recovered automatically if a single point failure occurs. The point can be an interface, a board, a device, or a link.


A data backup technology through which a fully usable copy of a data object can be quickly generated. The duplicate contains the image of the data object at a point in time.

subnet mask

The technology used by the IP protocol to determine where network segment packets are destined for. The subnet mask is in binary format. Stored in a client, server, or router. The subnet mask matches the IP address.




thin provisioning

A mechanism that offers on-demand allocation of storage space.

timing snapshot

To create snapshots periodically to continuously protect data.


The configuration or layout of a network formed by the connections between devices on a local area network (LAN) or between two or more LANs.




variable prefetch

A cache prefetch strategy. The size of the data to be prefetched is the multiple for prefetching multiplied by the length of a read command. This strategy applies to the applications that require reading data of variable size in a certain order or to the situations where multiple subscribers read data concurrently but no fixed prefetch size can be set because the amount of pre-read data cannot be judged. An example is the streaming media demanded by multiple subscribers who use different bit rates.




working controller

The controller that reads data from and writes data onto LUNs in a storage array.

write back

A caching technology in which the completion of a write request is signaled as soon as the data is in cache, and actual writing to non-volatile media occurs at a later time. Write back includes an inherent risk that an application will take some action predicated on the write completion signal, and a system failure before the data is written to non-volatile media will cause media contents to be inconsistent with that subsequent action. For this reason, good write back implementations include mechanisms to preserve cache contents across system failures (including power failures) and to flush the cache at system restart time.

write through

A caching technology in which the completion of a write request is not signaled until data is safely stored on non-volatile media. Write performance with the write through technology is approximately that of a non-cached system, but if the data written is also held in cache, subsequent read performance may be dramatically improved.

Updated: 2019-05-15

Document ID: EDOC1000084105

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