Chapter 7. Block I/O
This chapter covers optimizing I/O settings in virtualized environments.
7.1. Block I/O Tuning
The
virsh blkiotune command allows administrators to set or display a guest virtual machine's block I/O parameters manually in the <blkio> element in the guest XML configuration.
To display current
<blkio> parameters for a virtual machine:
# virsh blkiotune virtual_machine
To set a virtual machine's
<blkio> parameters, use the virsh blkiotune command and replace option values according to your environment:
# virsh blkiotune virtual_machine [--weight number] [--device-weights string] [--config] [--live] [--current]
Parameters include:
weight- The I/O weight, within the range 100 to 1000.Increasing the I/O weight of a device increases its priority for I/O bandwidth, and therefore provides it with more host resources. Similarly, reducing a device’s weight makes it consume less host resources.
device-weights- A single string listing one or more device/weight pairs, in the format of
/path/to/device,weight,/path/to/device,weight config- Add the
--config live- Add the
--liveNote
The--live current- Add the
--current
For example, the following changes the weight of the
/dev/sda device in the liftbrul VM to 500.
# virsh blkiotune liftbrul --device-weights /dev/sda, 500Note
Use the
virsh help blkiotune command for more information on using the virsh blkiotune command.
