Method used to reclaim thin LUN space


You can use the following methods to reclaim thin LUN space:
1. Manually set the space size to zero.
In this method, use a command to set the space value of the released space on a host to zero and reclaim the space. During the operation, the thin LUN space is fully occupied. Before performing this operation, you must stop services on thin LUNs.
2. Enable a storage system to automatically reclaim the released space.
If the operating system on a host support thin LUNs, the operating system can identify the released space and deliver a specified SCSI command to a storage system. Then, the storage system will reclaim the released space.

Other related questions:
Introduction to Dorado thin LUN and thick LUN
SmartThin provides a storage management mode that supports on-demand resource allocation. Instead of allocating all storage space in advance, it first allocates certain storage space and dynamically allocates storage resources based on users' requirements (also called thin LUNs). The other type of storage resources that correspond to thin LUNs is thick LUN. The storage system uses the thin provisioning technology to allocate a fixed storage capacity to a LUN based on the capacity specified for the LUN upon its creation. For details, see: Basic Storage Principles. When using thin LUNs, set the capacity overload of LUNs to not less than 10% of the storage pool capacity. When a host initially reads data from and writes data to a storage system, thick LUNs deliver better performance whereas thin LUNs boasts higher space utilization.

How does an AR reclaim IP addresses
You can manually reclaim IP addresses that cannot be released due to exceptions. The reclaimed IP addresses become idle and can be re-allocated to clients. The command is as follows: reset ip pool { interfacepool-name | nameip-pool-name } { start-ip-address [ end-ip-address ] | all | conflict | expired | used } Conflicting, expired, and used IP addresses can be reclaimed.
To reclaim the allocated IP address of that has been bound to a MAC address, use the following method:
- For the global address pool
<Huawei> reset ip pool name pool1 used //Release the allocated IP address.
<Huawei> system-view   //If IP addresses are not bound to MAC addresses, you do not need to perform the following operations.
[Huawei] ip pool pool1
[Huawei-ip-pool-pool1] undo static-bind ip-address //Remove the static binding.
- For the address pool:
<Huawei> reset ip pool interface vlanif100 used //Release the allocated IP address.
<Huawei> system-view   //If IP addresses are not bound to MAC addresses, you do not need to perform the following operations.
[Huawei] interface vlanif 100  
[Huawei-Vlanif100] undo dhcp server static-bind ip-address  //Remove the static binding.
Note: If a used IP address is within the IP address range specified by the command, performing the preceding operations may cause unexpected logout.

LUN requirements for deduplication
When a thick LUN is created, the relationship between its physical and logical addresses has already been fixed. This does not meet deduplication requirements. For deduplication, you must modify the mapping relationship between the physical and logical addresses. In addition, deduplication requires space reclamation. The pointer of the thick LUN's logical address cannot be changed. Therefore, the space cannot be reclaimed.

Method used to format a LUN on the storage
1. The LUN must be formatted after the LUN is created on the storage device. 2. After the LUN is created on the storage device, it is automatically formatted on the storage device without manual intervention. 3. The used LUNs cannot be formatted manually.

Method used to set the LUN stripe depth
1. The stripe depth can only be set during LUN creation and cannot be modified after being created. 2. Go to the Create LUN dialog box. In the navigation tree, click the storage system node and choose Storage Resources > LUNs. In the right function pane, choose Create > LUN. The Create LUN dialog box is displayed. Set the parameters in the Create LUN dialog box.

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