Perform batch block discard

You can perform a batch block discard operation to discard unused blocks on a mounted file system.

Before you begin

  • The file system is mounted.
  • The block device underlying the file system supports physical discard operations.

Procedure

  • Use the fstrim utility:
    • To perform discard only on a selected file system, use: 
      # fstrim mount-point
    • To perform discard on all mounted file systems, use: 
      # fstrim --all
  • If you run the fstrim command on:
    • a device that does not support discard operations, or
    • a logical device (LVM or MD) composed of multiple devices, where any one of the device does not support discard operations, the following message displays: 
      # fstrim /mnt/non_discard
       
      fstrim: /mnt/non_discard: the discard operation is not supported