Red Hat Training

A Red Hat training course is available for Red Hat Enterprise Linux

14.5.17. Using blockresize to Change the Size of a Domain Path

blockresize can be used to re-size a block device of a domain while the domain is running, using the absolute path of the block device which also corresponds to a unique target name (<target dev="name"/>) or source file (<source file="name"/>). This can be applied to one of the disk devices attached to domain (you can use the command domblklist to print a table showing the brief information of all block devices associated with a given domain).


Live image re-sizing will always re-size the image, but may not immediately be picked up by guests. With recent guest kernels, the size of virtio-blk devices is automatically updated (older kernels require a guest reboot). With SCSI devices, it is required to manually trigger a re-scan in the guest with the command, echo > /sys/class/scsi_device/0:0:0:0/device/rescan. In addition, with IDE it is required to reboot the guest before it picks up the new size.
  • Run the following command: blockresize [domain] [path size] where:
    • Domain is the unique target name or source file of the domain whose size you want to change
    • Path size is a scaled integer which defaults to KiB (blocks of 1024 bytes) if there is no suffix. You must use a suffix of "B" to for bytes.