Performance-related questions

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CDS

  • API Reference
    • Disk Related Interfaces
  • Dedicated Cluster Operation Guide
    • Charge
    • Create a dedicated cluster
    • Create Cloud Disk Server in Dedicated Cluster
    • Expand Dedicated Cluster
    • View Dedicated Cluster Information
    • What Is a Dedicated Cluster
  • Disk Operation Guide
    • Basic Operations
      • Create cloud disks
      • Disk encryption
        • Encrypt Data Disk and Snapshot
        • Encrypt System Disk and Image
        • Encryption Overview
      • Format cloud disks
        • Format Disk Partition on Linux System
        • Format Disk Partition on Windows System
        • Overview
      • Monitor alarm
      • mount Cloud Disk Server
      • Recycle bin
      • Release cloud disks
      • Tag Management
      • Unmount Cloud Disk Server
    • Billing management
      • Renew cloud disks
      • Shift Charge
    • Elastic Operations
      • Burst performance capability
      • Change cloud disk type
      • Performance preconfiguration
        • Use Performance Pre-Configuration
        • What Is Performance Pre-Configuration
      • Resize cloud disks
        • Expansion Overview
        • Extend Disk Partition on Linux Data Disk
        • Extend Disk Partition on Linux System Disk
        • Extend Disk Partition on Windows Data Disk
        • Extend Disk Partition on Windows System Disk
  • FAQs
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      • Configure CDS CMD Tool
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    • Baidu Intelligent Cloud Block Storage Trusted Cloud
    • CDS Service Level Agreement (SLA V2_0)
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    • Disk Snapshot
      • Automatic snapshot
      • Create a custom image
      • Create CDS disk from snapshot
      • Cross-region replication
      • Delete a snapshot
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      • Snapshot Rollback
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Table of contents on this page
  • What is the maximum size of a single file that can be stored on a CDS cloud disk?
  • Do CDS cloud disk-related services limit the number of concurrent requests from users?
  • What types of disks does CDS cloud disk support?
  • Between local disks and CDS cloud disks, which performs better in sequential read/write and random read/write?
  • Does a CDS cloud disk support elastic capacity expansion?
  • What are the advantages of CDS cloud disks compared to local disks?
  • When creating a new CDS cloud disk from a snapshot, can the capacity of the new disk be larger than that of the original disk?
  • What is the maximum capacity supported by a CDS cloud disk?
  • Does a local disk support capacity expansion?
  • Does a CDS cloud disk support transfer between accounts?

Performance-related questions

Updated at：2025-11-03

What is the maximum size of a single file that can be stored on a CDS cloud disk?

CDS is a block device and has no inherent file size limit. The specific maximum size of a single file that can be stored depends on the file system type used by the user on the CDS disk. For example: Under Windows, the maximum size of a single file in the FAT32 file system is 4 GB; Under Linux, the maximum size of a single file in the ext3 file system is 2 TB. For more information, please refer to Reference Materials.

Do CDS cloud disk-related services limit the number of concurrent requests from users?

No restrictions are applied.

What types of disks does CDS cloud disk support?

CDS is a block storage device that can be mounted as a raw device to a BCC cloud server instance. Currently, CDS cloud disks are available in six types: enhanced SSD, general-purpose SSD, high-performance cloud disk, general-purpose HDD, high-throughput HDD, and previous-generation cloud disk (new purchases of previous-generation cloud disks and high-throughput HDDs are no longer supported).

Between local disks and CDS cloud disks, which performs better in sequential read/write and random read/write?

The read and write speed of a local disk depends on various factors, such as the type of disk medium and whether RAID is configured. Comparing read/write speeds requires evaluating multiple scenarios (such as network bandwidth and file size). Hence, it cannot be conclusively determined which is superior.

Does a CDS cloud disk support elastic capacity expansion?

Currently, public cloud CDS products support elastic online capacity expansion. For detailed expansion operations, please refer to [CDS Disk Capacity Expansion](CDS/Disk Operation Guide/Elastic Operations/Resize cloud disks/Expansion Overview.md).

What are the advantages of CDS cloud disks compared to local disks?

  • The backend of CDS uses distributed storage with multiple replicas to ensure high reliability. On the other hand, if a local disk fails (as hard disks have a finite number of read/write cycles), data may be lost.
  • CDS decouples storage from computing resources, preventing file read/write operations from over-consuming other resources.
  • CDS can be attached to different virtual machines, whereas a local disk can only be associated with one virtual machine.

When creating a new CDS cloud disk from a snapshot, can the capacity of the new disk be larger than that of the original disk?

Yes, you may choose according to your requirements.

What is the maximum capacity supported by a CDS cloud disk?

A single CDS cloud disk supports a maximum storage capacity of 32 TB. You can attach up to 5 CDS cloud disks as data disks to the same cloud server. The maximum total CDS capacity per region is 160 TB. To request a higher quota, please submit a ticket.

Does a local disk support capacity expansion?

BCC servers support online capacity expansion for system disks and data disks of the CDS type. At present, expansion of local disks and non-CDS disks is not supported.

Does a CDS cloud disk support transfer between accounts?

CDS cloud disks cannot be transferred between accounts. Likewise, server transfers between accounts are not supported. To move data, please consider using the following methods:

  • For system disks: Create a custom image from the cloud server under your account, share the image with another Baidu AI Cloud account, then create a new server from this shared image in the target account. For detailed steps, please refer to [Using Images](BCC/Operation guide/Image/Create a custom image.md).
  • Data can be directly transferred over the public network.

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