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[N8000 Parameter Configuration]How to choose parameters for creating a LUN?

Created: Nov 25, 2013 09:39:10Latest reply: Nov 25, 2013 09:40:23 2037 1 0 0 0

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When creating a LUN, set relevant parameters based on the descriptions provided in this section.

Parameter Description

Parameter	Description	Setting
Name	This parameter indicates the RAID group whose LUN is to be created.	Select the created RAID group from the drop-down list box. NOTE: If the RAID group that the planned LUN belongs to is not in the drop-down list box, click Create RAID Group to create a new RAID group.
Level	This parameter indicates the RAID group level whose LUN is to be created.	-
Max. Sequential Free Capacity (GB)	This parameter indicates the capacity of the RAID group. NOTE: The capacity of the created LUN cannot be larger than the capacity of the RAID group that the created LUN belongs to.	-
Name	This parameter indicates the name of the LUN.	When setting the name of the LUN, note the following: The name of each LUN must be unique in the storage system. The name of the LUN consists of DBC-case alphabetic letters, DBC-case numbers, underscores or hyphens, and it contains 1 to 32 characters.
Number	This parameter indicates the number of LUNs created in batches.	The value ranges from 1 to 100.
Capacity	This parameter indicates the capacity of the new LUNs.	When setting this parameter, note the following: The value entered in the first text box after Capacity must be an integer. The maximum capacity of a LUN is the available capacity of the RAID group. Select 0 KB or 512 KB from the second drop-down list box after Capacity. The unit of the capacity can be MB, GB, TB, or KB.
Stripe Depth (KB)	This parameter indicates the stripe depth of a LUN. NOTE: The stripe depth affects the I/O performance of the storage device. Therefore, select the stripe depth appropriately according to different application scenarios. If the storage system is used for storing a large number of sequential data, a larger stripe depth (64 KB) is recommended. If the storage system is used for storing a large number of random data, a smaller stripe depth (32 KB) is recommended.	The value of the stripe depth can be 4 KB, 8 KB, 16 KB, 32 KB, 64 KB, 128 KB, 256 KB, or 512 KB. The default value of the stripe depth is 64 KB. The unit of the stripe depth is KB. NOTE: This parameter cannot be modified after configuration. Before creating a LUN, plan the stripe depth.
Owning Controller	This parameter indicates the owning controller on which the LUN is to be created. To ensure data consistency, the owning controller has precedence to handle all the host I/O requests of the LUN.	The value of this parameter can be: Controller A Controller B Auto Selected

Table 1 Advanced information

Parameter	Description	Setting
Prefetch Strategy	This parameter indicates the method to read the data on a LUN. When the storage system reads the data on the LUN, the storage system sends the data from the disk to the cache in advance according to the configured policy. NOTE: If you are familiar with the application scenarios of the storage device, you can use the fixed prefetch or variable prefetch strategy according to the actual condition. Otherwise, the intelligent prefetch is recommended. Constant Prefetch Value is suitable for the sequential read applications that have a fixed size. For example, in the multi-user streaming media video on demand (VOD) application, the streaming media files on the servers have the same code stream. Variable Prefetch Multiple is suitable for the sequential read applications that have an unfixed size, or for the multi-user concurrent read applications whose pre-read amount cannot be determined and cannot be set by fixed prefetch amount. For example, in the multi-user streaming media VOD application, the streaming media files on the servers have different code streams. Intelligent Prefetch is suitable for single-stream read applications and for the read applications that cannot be determined sequential or random, for example, read and write of files. None is suitable for the random read applications or for the applications that are already set with a prefetch strategy, for example, database applications.	The value of the prefetch strategy can be: None The storage system reads the data according to the prefetch length specified in the I/O request, that is, the prefetch strategy is not adopted. This setting is suitable for random read applications or for applications that are already set with a prefetch strategy, such as database applications. If a prefetch strategy is not used, the read performance is degraded. Using intelligent prefetch strategy is recommended. Fixed prefetch or alterable prefetch strategies can be used with application scenarios involving large amounts of sequential data. Intelligent The system software controls the prefetch amount by calculating the proper value. In the Intelligent prefetch mode, the storage system prefetches the data at the end of the chunk where the host request resides. Constant Prefetch Value When a storage system reads data on a LUN, it reads the data from the cache according to a constant prefetch length rather than the prefetch length specified in the I/O request. Variable Prefetch Multiple When a storage system reads the data on a LUN, it reads the data from the cache according to the multiples of the prefetch length specified in the I/O request.
Write Strategy	This parameter indicates the method by which data is written on a LUN. NOTE: The Write Back strategy is available only in the dual-controller status.	The value of this parameter can be: Write Through Data is directly written into the disk. The disk is accessed in each write operation and has a low performance but high reliability. Write Back, Mirroring Data is written into the local memory and the peer memory at the same time. The performance and reliability are high. Write Back, No Mirroring Data is written only into the local memory. The performance is high and the reliability is medium. Write Back Mandatory, Mirroring When the storage system encounters certain faults, for example, a single-power fault or single-fan fault, for example, the data is not written to the disk but written to the local cache and the peer cache at the same time. Write Back Mandatory, No Mirroring When the storage system encounters certain faults, a single-power fault and single-fan fault, for example, the data is not written to the disk but written to the local cache.

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user_1745 Created Nov 25, 2013 09:40:23

Thanks.

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