|Elastic cloud disk capability||Starting in May, 2018, all data disks purchased with CVMs are elastic cloud disks, which support unmounting and remounting on CVMs.|
|Cloud disk performance limits||I/O performance is in effect concurrently.
For example, a SSD with 1TB and a maximum random IOPS of up to 26,000 means that its IOPS for both reads and writes can reach this value. Meanwhile, because of multiple performance limits, if the I/O block size is 4KB/8KB in this example, I/O can reach the maximum IOPS; if its block size is 16KB, I/O cannot reach the maximum IOPS (throughput has already reached the limit of 260MB/s).
|The number of elastic cloud disks that can be mounted on one CVM||Maximum of 20 disks.|
|Snapshot quota of a single region||64 + the number of cloud disks in the region * 64 (units).|
|Limit on cloud disks mounted on CVMs||CVMs and cloud disks must be in the same availability zone.|
|Snapshot rollback limit||Snapshot data can only be rolled back to the source cloud disk where the snapshot was created.|
|Limit on the type of cloud disks created using snapshots||You can only use data disk snapshots to create new elastic cloud disks.|
|Limit on the size of cloud disks created using snapshots||The capacity of the new cloud disk created using snapshots must be larger than or equal to that of the snapshot source disk.|
|Cloud disk repossession when payment is in arrears||If the elastic cloud disk with monthly subscription expires and is not renewed within 7 days, the system will forcibly unbind the mounting relationship between this cloud disk and the CVM, and will repossess it to the recycle bin. For information on specific mechanism for repossession, see Arrears Description.
Currently, when mounting a cloud disk, the system automatically activates the automatic renewal function for elastic cloud disks, to prevent service interruption that may happen if you forget to renew.