openstack team mailing list archive

[John Griffith <john.griffith@xxxxxxxxxxxxx>]

On Tue, May 14, 2013 at 9:06 AM, Chris Bartels <chris@xxxxxxxxxxxxxxxxxxxxxx
> wrote:

> Hi,****
>
> ** **
>
> I have questions regarding this part of the Grizzly install guide that’s
> up on github:****
>
> ** **
>
> **·         **Finally, don't forget to create a volumegroup and name it
> cinder-volumes:****
>
> **·         **dd if=/dev/zero of=cinder-volumes bs=1 count=0 seek=2G****
>
> **·         **losetup /dev/loop2 cinder-volumes****
>
> **·         **fdisk /dev/loop2****
>
> **·         **#Type in the followings:****
>
> **·         **n****
>
> **·         **p****
>
> **·         **1****
>
> **·         **ENTER****
>
> **·         **ENTER****
>
> **·         **t****
>
> **·         **8e****
>
> **·         **w****
>
> **·         **Proceed to create the physical volume then the volume group:
> ****
>
> **·         **pvcreate /dev/loop2****
>
> **·         **vgcreate cinder-volumes /dev/loop2****
>
> *Note:* Beware that this volume group gets lost after a system reboot.
> (Click Here<https://github.com/mseknibilel/OpenStack-Folsom-Install-guide/blob/master/Tricks%26Ideas/load_volume_group_after_system_reboot.rst>to know how to load it after a reboot)
> ****
>
> ** **
>
> First, I don’t know what all those commands are doing, in particular with
> the dd stuff, and I’m reluctant to be doing stuff with that which I don’t
> understand, so if someone could explain what that’s all about I’d
> appreciate it. If that’s how it _*must*_ be done, I’d like to know.****
>
> ** **
>
> Secondly, I’m wondering if I could make life easier and not have to bother
> with the extra stuff regarding making the vg come back after reboot, which
> the instructions link to how to do, if I were to simply do the cinder vg
> with the installer & install Ubuntu with 100GB (out of 1000GB) of the disk
> made available to the guided LVM partitioning during the initial install,
> and use the rest as a cinder-volumes vgcreate’d group that gets mounted
> normally at each boot like everything else does.****
>
> ** **
>
> Wouldn’t that work? Seems easier to me.****
>
> ** **
>
> Please advise.****
>
> ** **
>
> Thanks,****
>
> Chris****
>
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>
> Hey Chris,

What's listed above is standard unix commands to build a loop-back device
file that can be used as a Physical Volume to build Volume Groups.  To be
honest, this isn't really how you should deploy Cinder in a real
environment, but it really just for testing and things like Devstack.

For a production setup, you'd actually want to have a raw disk or two on
the system, add them as an LVM Physical Volume.  The create the Volume
Group, in other words the only steps you would need are:

    pvcreate /dev/sdc (or some disk or partition that you have available)
    vgcreate cinder-volumes /dev/sdc

That's about it, that will give you dedicated partitions/volume groups and
it will persist over reboots.  I'd also suggest you read up a big on LVM to
get a better idea of what those commands do and how all of this works.

Hope that helps,
John