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Cloud Parallel File Storage:Scale out a file system

Last Updated:Feb 11, 2026

The capacity you set when creating a Cloud Parallel File Storage (CPFS) General-purpose file system is its maximum usable capacity. When the file system is full, you cannot write new data. To avoid write failures, scale out the file system before it reaches capacity.

Prerequisites

A CPFS General-purpose Edition file system has been created. For more information, see Create a file system.

Usage notes

  • You can scale out a file system only when it is in the running state.

  • The time required to scale out a file system depends on the scaling step size. A scale-out operation with a step size of 1,200 GiB takes about 10 minutes. A larger step size increases the time required, up to a maximum of about 30 minutes.

  • File systems can only be scaled out, not scaled in. The scaling step size is 1,200 GiB. A file system can be scaled out to a maximum capacity of 1 PiB.

  • When a file system nears capacity, high file fragmentation can degrade its performance. To prevent this, scale out the file system before its usage reaches 90%.

  • For optimal file system performance, balance the data after scaling out the CPFS General-purpose Edition. The balancing procedure consumes some disk and network bandwidth, which may cause a slight decrease in performance. To use this feature, submit a ticket.

    • The time required for balancing depends on the amount of historical data. If you have a large amount of data, the procedure may take a long time.

    • In cases of extreme data imbalance, the total capacity and usage reported by the df command and shown in the console might appear to decrease. This does not affect data security or access performance.

    • If you do not balance the data, service latency may increase as more data is written.

Procedure

  1. Log on to the NAS console.

  2. In the left-side navigation pane, choose File System > File System List.

  3. In the top navigation bar, select a region.

  4. Find the target file system and click 3 > Upgrade in the Actions column.

    Note

    File systems can only be scaled out, not scaled in. The scaling step size is 1,200 GiB. A file system can be scaled out to a maximum capacity of 1 PiB.

  5. In the Capacity of CPFS File System section of the CPFS (Pay-as-you-go) | Upgrade/Downgrade page, drag the slider to adjust the capacity.

    Note

    To ensure stable performance after a scale-out, increase the total capacity by at least 10%.

  6. Click Buy Now, and follow the on-screen instructions to complete the purchase.

API usage

Call the UpgradeFileSystem operation to scale out the capacity of a CPFS General-purpose Edition file system.

References