[PDF] Parallels Server 5 Bare Metal

Configuring the Disk I/O Bandwidth
Managing Resources
In Parallels Server Bare Metal, you can configure the bandwidth virtual machines and Containers
are allowed to use for their disk input and output (I/O) operations. Limiting the disk I/O bandwidth
can help you prevent the situations when high disk activities in one virtual machine or Container
(generated, for example, by transferring huge amounts of data to/from the virtual machine or
Container) can slow down the performance of other virtual machines and Containers on the
Parallels server.
By default, the I/O bandwidth limit for all newly created virtual machines and Containers is set to 0,
which means that no limits are applied to any virtual machines and Containers. To limit the disk I/O
bandwidth for a virtual machine or Container, you can use the --iolimit option of the pctl
set command. For example, the following command sets the I/O bandwidth limit for the MyVM
virtual machine to 10 megabytes per second (MB/s):
# pctl set MyVM --iolimit 10
Set up iolimit: 10
The VM has been successfully configured.
To set the limit for a Container, just specify its ID instead of the virtual machine name and the -save
option to save the changes to the Container configuration file, for example:
# pctl set 101 --iolimit 10 --save
Set up iolimit: 10485760
Saved parameters for Container 101
By default, the limit is set in megabytes per second. However, you can use the following suffixes to
use other measurement units:
• G: sets the limit in gigabytes per second (1G).
• K: sets the limit in kilobytes per second (10K).
• B: sets the limit in bytes per second (10B).
Note: In the current version of Parallels Containers, the maximum I/O bandwidth limit you can set for a
virtual machine and Container is 2 GB per second.
To check that the I/O speed limit has been successfully applied to the MyVM virtual machine and
Container 101, use the pctl list command:
# pctl list MyVM -o iolimit
10
# pctl list 101 -o iolimit
IOLIMIT
10485760
At any time, you can remove the I/O bandwidth limit set for the MyVM virtual machine and Container
101 by running these commands:
# pctl set MyVM --iolimit 0
Set up iolimit: 0
The VM has been successfully configured.
# pctl set 101 --iolimit 0 --save
Set up iolimit: 0
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