This module will discuss the guidelines and benefits for creating RAID Groups, Pools and configuring traditional, thick and thin LUNs.
This lesson covers the guidelines and configuration steps for creating RAID Groups and Traditional LUNs.
Shown here is the main Storage Provisioning window in Unisphere. The page offers several options for provisioning the storage on the system. In the Wizards section at the top right of the screen are the main tools for provisioning storage to FILE or BLOCK devices. The “Disk Provisioning Wizard for File”automates the provisioning of storage to be used for FILE storage operations. The “Storage Assignment Wizard for Block” automates the provisioning of storage to be used for BLOCK storage operations.A more manual method for provisioning the storage is available by selecting the “Storage Pools” option. Using this method offers more control of storage provisioning for customized provisioning needs. This method allows a selection for creating “Pools” of storage that can use the Advanced Data Services such as FAST, Thin and Thick LUNs and Compression which will be discussed further in this module. Storage can also be provisioned into “RAID Groups” for the creation of Traditional LUNs which will also be discussed further in this module. Storage provisioned in “Pools” that utilize Advanced Data Services or “RAID Groups” can then be allocated and used for FILE storage or BLOCK storage operations.
To configure a RAID group, select “Storage“ from the menu and choose “Storage Pools” By default the “Pool” tab is highlighted so users must select the “RAID Groups” tab and then “Create”. Users configure the RAID group parameters for “Storage Pool ID”, “RAID Type”, and the “Number of Disks” using the dropdown menus available from the “General” tab. By default, Unisphere will select the disks that will be used in the group automatically as shown by the “Automatic” radio button, however, users have the option to select the disk “Manually” as well if needed. Note the checkbox for “Use Power Saving Eligible Disks” which is not present when creating a “Pool”The “RAID Group Advanced Parameters” contains two configurable parameters.If selected, the “Automatically delete after last LUN is Unbound” will destroy this RAID Group after all LUNs belonging to this RAID Group are unbound. When cleared, the RAID Group is not destroyed. If selected, the “Expansion/Defragmentation Priority” will set the relative importance of expanding or defragmenting a RAID Group. Valid selections are Low, Medium, and High.Users can also select the “Allow Power Savings” parameters for the RAID Group if the group contains eligible disks.
To provision storage for File quickly and easily, open the Storage page and click on “Disk Provisioning Wizard for File” under Wizards. The Wizard has two modes of operation, Express and Custom. With Express mode selected the wizard will configure all of the VNX storage automatically using Best Practices. All of the storage provisioned will be allocated for File storage, no storage will be reserved for other hosts. The wizard displays several screens providing a breakdown of the allocation of disks, and a task status for the provisioning to complete.The wizard performs provisioning by selecting the available disks and creating RAID Groups. Traditional LUNs are then created from the RAID Groups.
Using the provisioning wizard with Custom mode selected, the wizard will provides the operator more control of the VNX storage allocation. The custom provisioning tool only allows three RAID types; RAID5 for Capacity, RAID 6 for Protection, and RAID 1/0 for Performance. If other RAID types are required, they must be configured outside of the Provisioning Wizard tool. The Storage Provisioning Wizard allows hot spares and reserve disks to be configured. It will report any drives that are not set to be allocated. Hot spares are important to have as they temporarily replace a failed drive until a replacement can be installed. Reserving disks for future use is important if the user desires to provision disks to other hosts now or in the future. They can also be provisioned to the VNX platform for File at a later date. Once all the provisioning options are selected, the wizard displays the status of the provisioning.As with the Express mode, the Custom mode provisions storage by creating RAID Groups and Traditional LUNs.
This lesson covers the process of creating Pool, Thin and Thick LUNs.
Similar to a RAID Group, Pools can be expanded to increase the usable capacity. Right click on the pool, select “Expand”. From the “Expand Storage Pool “ window, select the number of disks by using the dropdown arrow. Available disks are selected “Automatically’ or the user can select the “Manual” radio button and move selected disks to the right window. Expansion progress can be viewed from the Thin Pool properties window.Large pools may not be able to be created in a single step. In addition, a large number of drives may not be added to a pool at one time. This restriction is to allow for the Pool to initialize and become fully functional on-demand. The maximum number of drives that can be used to create or add-to a pool at one time is model dependent.
The capacity of a thick LUN, like the capacity of a RAID group LUN, is distributed equally across the disks in the pool on which you create the LUN. This behavior changes once data is added from hosts and additional disks are added to the Pool. Then all incoming data will be added to the new disks only until all disks are equally populated again.The amount of physical space allocated to a thick LUN, like the capacity of a RAID group LUN, is the same as the user capacity that the server’s operating system sees. A thick LUN uses slightly more capacity than the amount of user data written to it due to the metadata required to reference the data. Unlike a thin LUN, a thick LUN can never run out of space.
The primary difference between a thin LUN as compared to traditional LUNs and thick pool LUNs is that thin LUNs present more storage to an application than is physically allocated. Thin LUNs incrementally add to their in-use capacity. When a thin LUN requires additional physical storage, capacity is non-disruptively and automatically added from a storage pool, that is, Thin LUNs consume storage as needed from the underlying pool.
Listed are the key points covered in this module.
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