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Taikun OCP Guide

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Rate-limit volume copy bandwidth

When you create a new volume from an image or an existing volume, or
when you upload a volume image to the Image service, large data copy may
stress disk and network bandwidth. To mitigate slow down of data access
from the instances, OpenStack Block Storage supports rate-limiting of
volume data copy bandwidth.

Configure volume copy
bandwidth limit

To configure the volume copy bandwidth limit, set the
volume_copy_bps_limit option in the configuration groups
for each back end in the cinder.conf file. This option
takes the integer of maximum bandwidth allowed for volume data copy in
byte per second. If this option is set to 0, the rate-limit
is disabled.

While multiple volume data copy operations are running in the same
back end, the specified bandwidth is divided to each copy.

Example cinder.conf configuration file to limit volume
copy bandwidth of lvmdriver-1 up to 100 MiB/s:

[lvmdriver-1]
volume_group=cinder-volumes-1
volume_driver=cinder.volume.drivers.lvm.LVMVolumeDriver
volume_backend_name=LVM
volume_copy_bps_limit=104857600

Note

This feature requires libcgroup to set up blkio cgroup for disk I/O
bandwidth limit. The libcgroup is provided by the cgroup-tools package
in Debian and Ubuntu, or by the libcgroup-tools package in Fedora, Red
Hat Enterprise Linux, CentOS, openSUSE, and SUSE Linux Enterprise.

Note

Some back ends which use remote file systems such as NFS are not
supported by this feature.

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