[Openstack] [OpenStack][cinder]Does cinder allocate disk to the volumes dynamically?

Sean McGinnis sean.mcginnis at gmx.com
Wed Nov 28 16:03:38 UTC 2018

On Wed, Nov 28, 2018 at 04:10:21PM +0330, Soheil Pourbafrani wrote:
> When I installed OpenStack using PackStack, the size of LVM group was 20G
> but I could create 18 volume each of which 20G size (so in the PackStack
> the Cinder allocate volumes dynamically), but installing OpenStack from
> repository, the Cinder allocate disk to volume statically because I have
> volume group in size 140G but I only can create 7 volume of size 20G. So
> How Can I configure Cinder to allocate disk dynamically?

Not sure why you would be seeing a difference, but the default for Cinder is to
thin provision volumes.

This is controller through the following option in cinder.conf:

    # Use thin provisioning for SAN volumes? (boolean value)
    #san_thin_provision = true

Specific to LVM there is also the type option:

    # Type of LVM volumes to deploy; (default, thin, or auto). Auto defaults to
    # thin if thin is supported. (string value)
    # Possible values:
    # default - Thick-provisioned LVM.
    # thin - Thin-provisioned LVM.
    # auto - Defaults to thin when supported.
    #lvm_type = auto

With the "auto" setting, that should thin provision the volumes unless you had
already configured the volume group ahead of time to not support it. That's
probably the most likely thing I can think of.


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