Functions

Disk Types and Performance

EVS disks are classified into different types based on performance. Major performance metrics include IOPS, throughput, and read/write I/O latency. For details, see Disk Types and Performance.

Device Types

EVS device types are classified into VBD and SCSI based on whether advanced SCSI commands are supported. For details, see Device Types.

VBD is the default EVS device type. VBD EVS disks only support basic SCSI read/write commands.

SCSI EVS disks support transparent SCSI command transmission and allow the server OS to directly access the underlying storage media. SCSI EVS disks support both basic and advanced SCSI commands.

Data Disk Initialization

After you attach an EVS disk to a server, you need to initialize the disk before you can use it. For details, see Initialization Overview.

System Disk: System disks are automatically created and initialized during the server creation. The default disk partition style is master boot record (MBR).

Data Disk: If a data disk is created along with a server, it will be automatically attached to the server. If a data disk is created separately, you need to manually attach it to a server.

Regardless of how a data disk is attached, you must initialize it before using it. Choose an appropriate partition style based on your service plan.

Disk Capacity Expansion

If your disk space is insufficient, you can expand the disk capacity. Both system disks and data disks can be expanded. You can expand a system disk to up to 1 TB and expand a data disk to up to 32 TB. For details, see Expansion Overview.

You can expand the capacity of an EVS disk in two steps:

Step 1: Expand the disk capacity on the console.

Step 2: Log in to the server and extend the partitions and file systems.

Disk Sharing

A shared EVS disk is a block storage device that can be attached to multiple cloud servers for concurrent reads/writes. Shared disks feature high concurrency, high performance, and high reliability. They are usually used for enterprise critical applications that require cluster deployment and high availability (HA).

A shared EVS disk can be attached to a maximum of 16 servers. To share files, you need to first deploy a shared file system or a cluster management system, such as Windows MSCS, Veritas VCS, or CFS.

If you simply attach a shared EVS disk to multiple servers, data on the servers cannot be shared and may be overwritten.

For details, see Managing Shared EVS Disks.

Disk Backup

You can use cloud disk backup provided by Cloud Backup and Recovery (CBR) to back up your EVS disk data.

In case of a virus, accidental deletion, or software/hardware fault, you can restore data to any point when a backup was created to guarantee data integrity and security.

You can restore disk data to specific backup points. In addition, you can create new disks from backups so that the disks contain the backup data in the beginning.

See CBR Service Overview to learn about the backup principles.

Disk Snapshot

An EVS snapshot is a complete copy or image of the disk data taken at a specific time. Snapshot is a major data disaster recovery approach. You can create snapshots to quickly save disk data at specific time points.

If data is lost, you can roll back disk data to the state when a snapshot was taken. Alternatively, you can create new disks from snapshots. The new disks will contain the snapshot data once being created.

EVS is now deploying the snapshot function commercially in regions one by one. You may see the snapshot function in OBT (legacy snapshots) or commercial use (standard snapshots) in different regions, and there are differences between them. By default, a snapshot created in a commercially deployed region is a standard snapshot.

For details, see EVS Snapshot Overview.

Disk Type Change (OBT)

If the disk type no longer meet your service requirements, you can apply for changing it. For details, see Changing the Disk Type (OBT).

Recycle bin

When deleting an EVS disk, you can choose not to delete the disk immediately and move it to the recycle bin. This prevents data loss caused by accidental deletions. After a disk is moved to the recycle bin, you can either recover the disk from the recycle bin or delete it permanently. EVS recycle bin is disabled by default. You need to enable it before using it.

For details, see Recycle Bin Overview.

Disk Encryption

EVS enables you to encrypt data on newly created disks as required. It uses the industry-standard XTS-AES-256 cryptographic algorithm and keys to encrypt EVS disks. Keys used to encrypt EVS disks are provided by the Key Management Service (KMS) of Data Encryption Workshop (DEW), which is secure and convenient. You do not need to establish and maintain the key management infrastructure.

For details, see Managing Encrypted EVS Disks.

Disk Transfer

EVS disks can be transferred from one tenant to another. After a transfer succeeds, the disk belongs to the target tenant only. Only data disks can be transferred.

You can only call APIs to use disk transfer. For details, see Managing EVS Transfers.

Tag

Tags identify EVS resources for purposes of easy categorization and quick search. You can add tags when creating an EVS disk, or add and modify tags of an existing EVS disk.

For details, see Tag Overview.

Monitoring

Cloud Eye provides you with insights into your EVS disks. You can use Cloud Eye to automatically monitor EVS disks in real time and manage alarms and notifications to keep track of EVS performance metrics.

For details, see Basic EVS Monitoring Data.

Auditing

Cloud Trace Service (CTS) is a log audit service in the Huawei Cloud security solution. You can use CTS to record EVS operations, query event lists, and audit and backtrack historical operations.

For details, see Recording EVS Operations Using CTS.

Quotas

Quotas are enforced for cloud service resources to prevent unforeseen spikes in resource usage. There are preset quotas on the EVS disk quantity, EVS disk capacity, and EVS snapshot quantity. You can request for a larger quota if the existing quota does not meet your service requirements.

For details, see Querying EVS Resource Quotas.