|Enhanced SSD usage|| 1. Currently, Enhanced SSD is only available in Guangzhou Zone 3, Guangzhou Zone 4, Shanghai Zone 2, Shanghai Zone 3, Shanghai Zone 5, Beijing Zone 3, Beijing Zone 4, Chengdu Zone 1, Chongqing Zone 1, Nanjing Zone 1, and Nanjing Zone 2. It will be supported in more availability zones.
2. The performance of Enhanced SSD is only guaranteed when it’s mounted to S5, M5, SA2, IT3, and D3 models created after August 1, 2020, and all later generation models.
3. Enhanced SSD cannot be used as the system disk.
4. Enhanced SSD cannot be encrypted.
5. Enhanced SSD cannot be upgraded from other disk types.
|Elastic cloud disk capability||Starting from May 2018, all data disks purchased with CVMs are elastic cloud disks, which support unmounting from and remounting to CVMs. This feature is supported in all availability zones.|
|Cloud disk performances||I/O specification applies to both input and output performance at the same time.
For example, if a 1-TB SSD has a maximum random IOPS of 26,000, its means that both its read and write performance can reach this value. Due to performance limits, if the block size in this example is 4 KB or 8 KB, the maximum IOPS can be reached. If the block size is 16 KB, the maximum IOPS cannot be reached (throughput has already reached the limit of 260 MB/s).
|Max mountable elastic cloud disks per CVM||One CVM can have a maximum of 20 cloud disks mounted.|
|Mounting||A cloud disk can only be mounted to a CVM in the same availability zone.|
|Repossession of cloud disks in arrears||When a monthly-subscribed cloud disk expires and you do not renew it within 7 days after the expiry, it will be forcibly unmounted from the CVM (if any), and moved to the recycle bin. For details about the repossession mechanism, see Arrears.
Currently, when you mount a monthly-subscribed cloud disk to monthly-subscribed CVM, the following renewal method are available:
|Supported disk type||You can only use the data disk snapshot to create elastic cloud disks, while using the system disk snapshot to create a custom image.|
|Capacity of Created Cloud Disk||The capacity of the cloud disk created using a snapshot should be greater than or equal to that of the snapshot.|
|Snapshot rollback||Snapshot data can only be rolled back to the source cloud disk where the snapshot was created. If you want to create a cloud disk with data in an existing snapshot, see Creating Cloud Disks Using Snapshots.|
|Total snapshot size||No limit.|
|Snapshot quota in one region||64 + the number of cloud disks in the region * 64.|
|Scheduled snapshot policy quota in one region||A single Tencent Cloud account can set a maximum of 30 scheduled snapshot policies in each region.|
|Number of scheduled snapshot policies being associated with one cloud disk||A cloud disk can associate with a maximum of 10 scheduled snapshot policies in the same region.|
|Number of cloud disks associated with one scheduled snapshot policy||A scheduled snapshot policy can be associated with a maximum of 200 cloud disks in the same region.|