When you create a disk, you do two things: allocate space, place zeros
1, thick provision delay 0 :
the default creation format, when the disk is created, is directly from the disk Allocate Space , but retains data on the disk No Reset 0 . So when there is an I/O operation, only the zero operation is required.
Good disk performance, short time, suitable for pool-mode virtual desktops
2, thick provision 0 (thick):
Create a cluster-capable disk. When you create a disk, you allocate space directly from the disk, and 0 for the disk retention data. Therefore, there is no need to wait for direct execution when there is an I/O operation.
Disk performance is the best, long time, suitable for running a heavy application business of virtual machines
3. thin Provisioning (thin):
When the disk is created, the amount of space occupied by the disk is calculated based on the actual usage, that is, the number of points, in advance unallocated space , the disk is retained data Pail 0 , and the maximum size of the partition disk.
So when there is an I/O operation, space must be allocated before the space is zeroed to perform I/O operations. Disk performance degrades when there are frequent I/O operations
Disk performance is good when I/O is infrequent, and disk performance is poor when I/O is frequent. Short time, suitable for business application virtual machines with infrequent disk I/O
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About VMware Virtual machine disk types and differences