Creating a LUN

Prerequisites

• At least one storage pool has been created.
• You are an administrator or super administrator.

Context

Storage pool storage_pool_0 has been used to create LUNs vm_lun_0 and vm_lun_1 that belong to controller A and controller B, respectively.

Do not delete the preset LUN information about the storage system. Otherwise, the VM service fails.

• A thin LUN, a logical disk accessible to hosts, is configured with an initial capacity when created and then dynamically allocated required storage resources when its available capacity is insufficient.
• A thick LUN, a logical disk accessible to hosts, is allocated the specified capacity during the creation based on the automatic provisioning technology.

When a host initially reads data from and writes data to a storage system, thick LUNs deliver better performance and thin LUNs provide higher space utilization.

Procedure

1. Log in to DeviceManager.
2. Choose Provisioning > LUN.
3. Click Create.

   The Create LUN dialog box is displayed.

4. Set basic properties for the LUN.
   Table 4-8 LUN parameters

   Parameter	Description	Value
   Name	Name of a newly created LUN.	[Value range] The name must be unique. The name can contain only letters, digits, periods (.), underscores (_), and hyphens (-). The name must contain 1 to 31 characters. [Example] LUN001
   Description	Description of a LUN.	[Example] -
   Start ID	ID of a LUN. NOTE: The system automatically allocates an ID to a newly created LUN by default. If you want to manually set a LUN ID, do not select Automatic allocate. Instead, enter an ID manually. When creating a single LUN, the value you enter is the ID of the LUN. When creating LUNs in batches, the system automatically allocates an ID starting from the value you have entered to each LUN.	[Example] 2
   SmartThin	You can enable SmartThin to create thin LUNs. NOTE: SmartThin requires a license. If SmartThin is enabled, the storage system creates thin LUNs and dynamically allocates storage capacity to thin LUNs based on the actual capacity used by hosts instead of allocating all the preset capacity to thin LUNs, achieving on-demand allocation.	[Example] Disable
   Owning Storage Pool	Storage pool to which the LUN you are creating belongs. NOTE: If the storage system has no storage pool, click Create to create one.	[Example] StoragePool001
   Capacity	Capacity of a LUN. A user specifies the capacity when creating a LUN. When SmartThin is enabled, this parameter indicates the maximum capacity that can be allocated to a thin LUN. That is, the total storage resources dynamically allocated to the thin LUN cannot exceed the value of this parameter. When SmartThin is disabled, this parameter indicates the capacity allocated to a thick LUN at a time.	[Value range] The maximum capacity of thick LUNs must be less than or equal to the available capacity of the storage pool. The maximum capacity of thin LUNs must be less than or equal to its specifications. The system can create block-level LUNs. To create a block-level LUN, select capacity unit Blocks. One block is 512 bytes. [Example] 10 GB
   Use all the available capacity of the owning storage pool	If this option is selected, all free space of the owning storage pool is allocated to this LUN.	[Example] -
   Quantity	Number of LUNs created in batches. Set this parameter based on your need. NOTE: LUNs created in batches have the same capacity. The total capacity of LUNs created in batches must be less than or equal to the available capacity of the storage pool.	[Value range] 1 to 500 [Example] 5
   Manually specify the suffix	When creating multiple LUNs, the system automatically appends a suffix number to each LUN name for LUN distinction. You can manually set the start suffix number after selecting this option. NOTE: If this option is not selected, the suffix number starts at 0000 by default.	[Example] -
   Start Number	This parameter is valid after Manually specify the suffix is selected. From the configured start number, the system incrementally appends a suffix number to the name of each LUN for LUN distinction.	[Value range] 0 to (10000 – Number of LUNs to be created) NOTE: If you want to create 300 LUNs, the value range of the start number is 0 to 9700.

5. Optional: Set advanced properties for the LUN.
   1. Click Advanced.

      The Advanced dialog box is displayed.

   2. Set advanced properties for the LUN.

      Click the Properties and Tuning tabs to set related parameters.

      GUIs may vary with product versions and models. The actual GUIs prevail.

      Table 4-9 Properties parameters

      Parameter	Description	Value
      Owning Controller	Owning controller of a LUN NOTE: To allocate LUNs to controllers for load balancing, you are advised to select Auto select.	[Example] Auto select
      Initial Capacity Allocation Policy	Policy for the storage tier to allocate capacity to a LUN Automatic allocation: The storage system automatically allocates capacity to a LUN based on the percentage of the available capacity of the performance tier to that of the capacity tier. Capacity is allocated from the high performance tier only when the capacity of the performance tier and capacity tier is insufficient. Allocate from the high performance tier first: The storage system allocates capacity to a LUN from the high performance tier first. If the capacity of the high performance tier is insufficient, the storage system allocates capacity from other storage tiers, first from the performance tier and then from the capacity tier. Allocate from the performance tier first: The storage system allocates capacity to a LUN from the performance tier first. If the capacity of the performance tier is insufficient, the storage system allocates capacity from other storage tiers, first from the capacity tier and then from the high performance tier. Allocate from the capacity tier first: The storage system allocates capacity to a LUN from the capacity tier first. If the capacity of the capacity tier is insufficient, the storage system allocates capacity from other storage tiers, first from the performance tier and then from the high performance tier.	[Value range] The value can be Automatic allocation, Allocate from the high performance tier first, Allocate from the performance tier first, or Allocate from the capacity tier first. [Example] Automatic allocation [Default value] Automatic allocation
      Read Policy	Data read policy of a cache. The system supports the following read policies. Resident: suitable for random access. The storage system caches data as long as possible to improve the read hit ratio. Default: suitable for common access. The storage system strikes a balance between the read hit ratio and disk access performance. Recycle: suitable for sequential access. The storage system releases idle cache resources as soon as possible for other services to use.	[Value range] The value can be Resident, Default, or Recycle. [Example] Resident [Default value] Default
      Write Policy	Data write policy of a cache. The system supports the following write policies. Resident: suitable for random access. The storage system caches data as long as possible to improve the write hit ratio. Default: suitable for common access. The storage system strikes a balance between the write hit ratio and disk access performance. Recycle: suitable for sequential access. The storage system releases idle cache resources as soon as possible for other services to use.	[Value range] The value can be Resident, Default, or Recycle. [Example] Resident [Default value] Default
      Prefetch Policy	Read mode of a LUN. When reading data, the storage system prefetches required data from disks to the cache in advance according to a preset policy. The system supports the following prefetch policies: No prefetch: The storage system reads data based on the read length specified in the I/O request. As a low read hit ratio may lead to performance degradation, No prefetch is recommended for random read services. Intelligent prefetch: The storage system analyzes the continuity of read requests from hosts. If the read requests are continuous, the data following the current read request is prefetched from disks to the cache. In this way, the cache hit ratio can be increased. If they are not, the data is read directly from disks. This policy is applicable to the scenario where sequential reads and random reads coexist or to the read applications that cannot be determined sequential or random. Constant prefetch: A constant length of data is read from disks every time when the cache reads data from the disks. The length is user-defined, ranging from 0 to 1024 KB. Constant prefetch is applicable to the sequential read applications with fixed-size data blocks, for example, ring back tone (RBT) and requests initiated by multiple users for playing multimedia on demand at the same bit rate. Variable prefetch: The cache reads data from disks based on a multiple of the read length specified in the I/O request. The multiple is user-defined, ranging from 0 to 1024. This policy is applicable to sequential read applications with unfixed-size data blocks or multi-user concurrent read applications whose prefetch data amount cannot be determined, for example, requests initiated by multiple users for playing multimedia on demand at different bit rates.	[Value range] The value can be No prefetch, Intelligent prefetch, Constant prefetch, or Variable prefetch. [Example] Intelligent prefetch [Default value] Intelligent prefetch

   3. Click OK.

      The Create LUN dialog box is displayed.

6. Confirm the creation of the LUN.
   1. Click OK.

      The Execution Result dialog box is displayed, indicating that the operation succeeded.

   2. Click Close.