| 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>
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| 9 | <ph conkeyref="vbox-conkeyref-phrases/product-name"/> supports limiting of the maximum bandwidth used for
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| 10 | asynchronous I/O. Additionally it supports sharing limits through
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| 11 | bandwidth groups for several images. It is possible to have more
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| 12 | than one such limit.
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| 13 | </p>
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| 14 | <p>
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| 15 | Limits are configured using <userinput>VBoxManage</userinput>. The
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| 16 | example below creates a bandwidth group named Limit, sets the
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| 17 | limit to 20 MB per second, and assigns the group to the attached
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| 18 | disks of the VM:
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| 19 | </p>
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| 20 | <pre xml:space="preserve">VBoxManage bandwidthctl "VM name" add Limit --type disk --limit 20M
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| 21 | VBoxManage storageattach "VM name" --storagectl "SATA" --port 0 --device 0 --type hdd
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| 22 | --medium disk1.vdi --bandwidthgroup Limit
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| 23 | VBoxManage storageattach "VM name" --storagectl "SATA" --port 1 --device 0 --type hdd
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| 24 | --medium disk2.vdi --bandwidthgroup Limit</pre>
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| 25 | <p>
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| 26 | All disks in a group share the bandwidth limit, meaning that in
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| 27 | the example above the bandwidth of both images combined can never
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| 28 | exceed 20 MBps. However, if one disk does not require bandwidth
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| 29 | the other can use the remaining bandwidth of its group.
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| 30 | </p>
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| 31 | <p>
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| 32 | The limits for each group can be changed while the VM is running,
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| 33 | with changes being picked up immediately. The example below
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| 34 | changes the limit for the group created in the example above to 10
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| 35 | MBps:
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| 36 | </p>
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| 37 | <pre xml:space="preserve">VBoxManage bandwidthctl "VM name" set Limit --limit 10M</pre>
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| 38 | </body>
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| 39 |
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| 40 | </topic>
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