Dell EMC PowerVault MD 34XX/38XX Series Storage Arrays Administrator's Guide

Creating thin virtual disk from disk pool

1. In the AMW, select the Storage & Copy Services tab.
2. Select a Free Capacity node in a disk pool.
   The thin virtual disks are listed under the Disk Pools node.
3. Select Storage > Virtual Disk > Create > Virtual Disk.
   The Create Virtual Disk window is displayed.
4. Select Create thin virtual disk.
5. Use the New virtual capacity box to indicate the virtual capacity of the new virtual disk and Units to indicate the specific capacity units to use—MB, GB, or TB.
   The minimum virtual capacity is 32 MB.
6. In the Virtual disk name box, enter a name for the virtual disk.
7. To map hosts to virtual disks, select Map later.
   The virtual disk is not assigned a LUN and is not accessible by any hosts until you go to the Host Mappings tab and assign a specific host and LUN to this virtual disk.
8. To use flash SSD cache, select Use flash SSD cache.
   Flash SSD cache provides read-only caching of user-selected virtual disks on Solid-State Disks (SSDs) to further improve the read performance of those virtual disks beyond conventional hard drives. This process of copying data transparently off hard drives and on to high-performance SSDs improves application I/O performance and response times.

   The Use flash SSD cache check box is disabled if:

   • no SSD cache is available
   • the disk pool is comprised of only SSD physical disks
   • the disk pool has different data service attributes from the SSD cache
   • you selected Map Later

   NOTE: When you are creating a thin virtual disk, the Enable dynamic cache read prefetch option is not available.
9. Click Next.
10. Do one of the following:
    • Select Use recommended capacity settings, and click Next.
    • Select Choose your own settings and then select Customize capacity settings (advanced). Click Next and go to step 11.
11. Use the Preferred capacity box to indicate the initial physical capacity of the virtual disk and the Units list to indicate the specific capacity units to use—MB, GB, or TB.
    NOTE: The physical capacity is the amount of physical disk space that is currently reserved for write requests. The physical capacity must be at least 4 GB, and cannot be larger than 256 GB.

    Based on the value that you entered in the previous step, the Disk pool physical capacity candidates table is populated with matching repository virtual disks. New repository candidates returned either matches the capacity you specify, or be rounded up to the closest 4 GB increment to make sure all the repository capacity is usable.

12. Select a repository from the table.
    Existing repositories are placed at the top of the list.

    NOTE: The benefit of reusing an existing repository is that you can avoid the initialization process that occurs when you create a new one.
13. If you want to change the repository expansion policy or warning threshold, click View advanced repository settings.
    • Repository expansion policy – Select either Automatic or Manual. When the consumed capacity gets close to the physical capacity, you can expand the physical capacity. The MD storage management software can automatically expand the physical capacity, or you can do it manually. If you select Automatic, you also can set a maximum expansion capacity. The maximum expansion capacity allows you to limit the virtual disk’s automatic growth below the virtual capacity. The value for the maximum expansion capacity must be a multiple of 4 GB.
    • Warning threshold – In the Send alert when repository capacity reaches field, enter a percentage. The MD Storage Manager sends an alert notification when the physical capacity reaches the full percentage.
14. Click Finish.
    The Virtual Disk Successfully Created window is displayed.
15. Click OK.
    If you want to create another virtual disk, click Yes on the Do you want to create another virtual disk? . Perform any operating system modifications necessary on the application host so that the applications can use the virtual disk. For more information, see the MD Storage Manager Software Installation Guide for your operating system.