| 1 | <?xml version="1.0" encoding="UTF-8"?>
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| 2 | <!DOCTYPE topic
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| 3 | PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 4 | <topic xml:lang="en-us" id="storage-bandwidth-limit">
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| 5 | <title>Limiting Bandwidth for Disk Images</title>
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| 6 |
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| 7 | <body>
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| 8 | <p><ph conkeyref="vbox-conkeyref-phrases/product-name"/> supports limiting of the maximum bandwidth used
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| 9 | for asynchronous I/O. Additionally it supports sharing limits through bandwidth groups for several images. It is
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| 10 | possible to have more than one such limit. </p>
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| 11 | <p>Limits are configured using <userinput>VBoxManage</userinput>. The example below creates a bandwidth
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| 12 | group named Limit, sets the limit to 20 MB per second, and assigns the group to the attached disks of the VM: </p>
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| 13 | <pre xml:space="preserve">VBoxManage bandwidthctl "VM name" add Limit --type disk --limit 20M
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| 14 | VBoxManage storageattach "VM name" --storagectl "SATA" --port 0 --device 0 --type hdd
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| 15 | --medium disk1.vdi --bandwidthgroup Limit
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| 16 | VBoxManage storageattach "VM name" --storagectl "SATA" --port 1 --device 0 --type hdd
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| 17 | --medium disk2.vdi --bandwidthgroup Limit</pre>
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| 18 | <p>All disks in a group share the bandwidth limit, meaning that in the example above the bandwidth of
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| 19 | both images combined can never exceed 20 MBps. However, if one disk does not require bandwidth the other can use
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| 20 | the remaining bandwidth of its group. </p>
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| 21 | <p>The limits for each group can be changed while the VM is running, with changes being picked up
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| 22 | immediately. The example below changes the limit for the group created in the example above to 10 MBps: </p>
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| 23 | <pre xml:space="preserve">VBoxManage bandwidthctl "VM name" set Limit --limit 10M</pre>
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| 24 | </body>
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| 25 |
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| 26 | </topic>
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