Pinning and prepopulating LUNs in the Core
LUN pinning and prepopulation are two separate features configured through the Core that together determine how block data is kept in the blockstore on the Edge. When you pin a LUN in the Core configuration, you reserve space in the Edge blockstore that is equal in size to the LUN at the storage array. Furthermore, when blocks are fetched by the Edge, they remain in the blockstore in their entirety; by contrast, blocks in unpinned LUNs might be cleared on a first-in, first-out basis.
Pinning only reserves blockstore space; it does not populate that space with blocks. The blockstore is populated as the application server in the branch requests data not yet in the blockstore (causing the Edge to issue a read through the Core), or through prepopulation. The prepopulation functionality enables you to prefetch blocks to the blockstore. You can prepopulate a pinned LUN on the blockstore in one step; however, if the number of blocks is very large, you can configure a prepopulation schedule that prepopulates the blockstore only during specific intervals of your choice: for example, not during business hours. After the prepopulation process is completed, the schedule stops automatically.
Prefetch does not optimize access for VMs that contain any SE SPARSE (Space Efficient Sparse) format snapshots.
1. Choose Configure > Manage: LUNs to display the LUNs page.
2. Click the LUN configuration to display the configuration settings.
3. Select the Pin/Prepop tab.
4. To pin the LUN, select Pinned from the drop-down list and click Update.
When the LUN is pinned, the prepopulation settings are activated for configuration.