Dell POWERVAULT MD3600I - Manual (Page 106)

Changing Capacity On Existing Thin Virtual Disks
If the amount of space used by the host for read/write operations (sometimes called consumed capacity) exceeds the
amount of physical capacity allocated on a standard virtual disk, the storage array cannot accommodate additional
write requests until the physical capacity is increased. However, on a thin virtual disk, MD Storage Manager can
automatically expand physical capacity of a thin virtual disk. You can also do it manually using Storage → Virtual Disk
→
Increase Repository Capacity. If you select the automatic expansion option, you can also set a maximum expansion
capacity. The maximum expansion capacity enables you to limit the automatic growth of a virtual disk to an amount less
than the defined virtual capacity.
NOTE: Since less than full capacity is allocated when you create a thin virtual disk, insufficient free capacity may
exist when certain operations are performed, such as snapshot images and snapshot virtual disks. If this occurs,
an alert threshold warning is displayed.
Creating A Thin Virtual Disk From A Disk Pool
NOTE: You can create thin virtual disks only from disk pools, not from disk groups.
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:
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