|Enhanced SSD usage|| 1. Currently, Enhanced SSD is only available in some availability zones.
2. The performance of Enhanced SSD is only guaranteed when it’s attached to S5, M5, and SA2 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.
|Tremendous SSD usage|| 1. Currently, Tremendous SSD is only available in certain availability zones, as shown in the CBS purchase page. It will be supported in more availability zones.
2. Tremendous SSD can only be purchased with the Standard Storage Optimized S5se CVM instance.
3. Tremendous SSD cannot be purchased independently.
4. Tremendous SSD cannot be used as the system disk.
5. Tremendous SSD cannot be encrypted.
6. Tremendous SSD cannot be upgraded from other disk types.
|Elastic cloud disk capability||Starting from May 2018, all data disks purchased upon creation of CVMs are elastic cloud disks. You can detach them from and re-attach them 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, it 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 attachable elastic cloud disks per CVM||One CVM can have a maximum of 20 cloud disks attached.|
|Attaching||A cloud disk can only be attached to a CVM in the same availability zone.|
|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 cloud disk created using a snapshot||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 from which 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.|