Constraints

Capacity of a data disk

• High I/O: 10 GiB to 32,768 GiB
• General Purpose SSD: 10 GiB to 32,768 GiB
• Ultra-high I/O: 10 GiB to 32,768 GiB
• Extreme SSD: 10 GiB to 32,768 GiB

Disk performance

Common I/O

• Maximum IOPS per disk: 1,000
• Maximum throughput per disk: 40 MiB/s

Ultra-high I/O

• Maximum IOPS per disk: 20,000
• Maximum throughput per disk: 320 MiB/s

General Purpose SSD

• Maximum IOPS per disk: 20,000
• Maximum throughput per disk: 250 MiB/s

Disk creation restrictions on accounts

Permission requirement

The account used to create EVS disks must have the evs:volumes:create permission. For how to add permissions, see EVS Custom Policies

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 value varies with ECS types.

For details, see section "Can I Attach Multiple Disks to an ECS?" in the Elastic Cloud Server User Guide.

Maximum number of disks that can be attached to a BMS

60 (1 system disk and 59 data disks)

Device name

• System disk: /dev/vda, /dev/sda, and /dev/xvda
• Data disk: /dev/vd[b-z], /dev/sd[b-z], and /dev/xvd[b-z]

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. That is, 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, that is, its server can either be in the Running or Stopped state.

Disk deletion

Deletion of disks

• Pay-per-use disk:
  It can only be deleted when the following conditions are met:

  • The disk status is Available, Error, Expansion failed, Restoration failed, or Rollback failed.
  • The disk is not added to any replication pair in the Storage Disaster Recovery Service (SDRS). For any disk already added to a replication pair, you need to first delete the replication pair by referring to section "Deleting a Replication Pair" in the Storage Disaster Recovery Service User Guide and then delete the disk.
  • The disk is not locked by any service.
  • The shared disk has been detached from all its servers.

Tag

Maximum number of tags that can be added for a disk

10