Notes and Constraints¶
This section describes the constraints on using EVS.
Specifications¶
Resource Type | Item | Description |
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Disk performance | Major disk performance metrics include IOPS, throughput, and latency. | Different types of EVS disks have different performance. For details, see Disk Types and Performance. |
Security¶
Item | Description |
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Disk encryption |
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Quotas¶
You can log in to the console to view default quotas. You can to apply for a larger quota if needed.
Resource Type | Default Quota |
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Tags | 10 |
Disks | Default quotas vary depending on regions. See the quotas shown on the console. |
Disk capacity (GB) | |
Snapshots |
Operations¶
Scenario | Item | Description |
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Disk creation | Maximum number of disks that can be created at a time | 100 |
Disk creation from snapshot |
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Disk creation from backup |
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Disk creation from image |
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Device type | The device type of a disk cannot be changed after the disk has been created. | |
Disk sharing | The sharing attribute of a disk cannot be changed after the disk has been created. | |
Disk encryption | The encryption attribute of a disk cannot be changed after the disk has been created. | |
Disk attachment | Constraints on region and AZ | The disk and server must be in the same region and AZ. |
Maximum number of servers that a non-shared disk can be attached to | 1 | |
Maximum number of servers that a shared disk can be attached to | 16 | |
Maximum number of disks that can be attached to an ECS | This number varies depending on the ECS type. For details, see section "Can I Attach Multiple Disks to an ECS?" in the Elastic Cloud Server User Guide. For a BMS, a maximum of 60 EVS disks (1 system disk and 59 data disks) are supported. | |
Device name |
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Disk capacity expansion | Capacity expansion | Disk capacity can be expanded, but cannot be reduced. |
Capacity expansion of non-shared disks | Some server OSs support the capacity expansion of non-shared, In-use disks. For details, see Expanding Capacity for an In-use EVS Disk. | |
Capacity expansion of shared disks | A shared disk must be detached from all its servers before expansion. This means that the shared disk status must be Available. | |
Expansion increment | 1 GiB | |
Disk detachment | System disk detachment | A system disk can only be detached offline, which means that the server must be in the Stopped state. |
Data disk detachment | A data disk can be detached online or offline, meaning that its server can either be in the Running or Stopped state. | |
Disk deletion | Deletion of disks |
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Snapshot creation | / |
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Snapshot data rollback to disk | / |
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Snapshot deletion | / |
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