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How to set up Cinder volumes correctly?

asked 2014-10-29 07:59:59 -0500

mr_element gravatar image

updated 2014-10-29 10:39:17 -0500

BrunoGraz gravatar image

Hi, I am working on a server with a single physical HDD. I have installed Ubuntu 14.04 and using command:

sudo lsblk -o NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL

I get this output:

NAME   FSTYPE   SIZE MOUNTPOINT LABEL
sda           837.9G
├─sda1 ext4   832.9G /
├─sda2            1K
├─sda4         1023K
└─sda5 swap       5G [SWAP]
sr0            1024M

I have set up the Cinder service but when I try inputting this command:

pvcreate /dev/sda1

I get as output: Can't open /dev/sda1 exclusively. Mounted filesystem?

What have I missed and how to set the volume(s) correctly?

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You should "pvcreate /dev/sda" without specify any partitions on it. Not sda1 but sda.

Ramirezkiv gravatar imageRamirezkiv ( 2016-01-21 07:03:07 -0500 )edit

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answered 2014-10-30 06:48:59 -0500

You can add one more drive to that instance. Let us say "dev/sdb". Then you can do pvcreate /dev/sdb

Best option is:

  1. Create a loopback device in your machine.
  2. Create physical volume (using pvcreate) on that device.
  3. Then create Volume Group on top of that "vgcreate".

How to create:

  1. Create a 8G loopback device using: dd if=/dev/zero of=NewDrive.img bs=1G count=8

  2. Create loop back device: losetup /dev/loop0 NewDrive.img

  3. Then create physical volume on it: pvcreate /dev/loop0

  4. Now you can create volume group: vgcreate "cinder-volumes" /dev/loop0

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answered 2015-04-07 03:17:56 -0500

Kannan Raman gravatar image

updated 2015-04-07 03:18:43 -0500

@BharatKumarKobagana, your steps are perfect but, it fails in few systems saying "No such File or Directory" during physical volume creation. For that we found a solution where we have to format the file device and then need to be assigned back to loopback device.

STEPS:

  1. Create a 8G loopback device using: dd if=/dev/zero of=NewDrive.img bs=1G count=8

    #Additional Step

  2. Device file format for some ext3 or other: mkfs.ext3 NewDrive.img

  3. Create loop back device: losetup /dev/loop0 NewDrive.img

  4. Then create physical volume on it: pvcreate /dev/loop0

  5. Now you can create volume group: vgcreate "cinder-volumes" /dev/loop0

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answered 2014-10-29 09:51:17 -0500

Alex Z gravatar image

In your case /dev/sda1 is already mounted as root file system - you cannot make PV on it. It will be better if you will have a second HDD, or even to have RAID for it (depending on your needs). If you want only prove idea you need to make empty partition for PV.

for example. make /dev/sda1- for root fs - I think 20GB will be enough /dev/sda2 - for SWAP for example 5G as in your case /dev/sda3 - all other space - is about 800G for PV for cinder-volumes

when you make pvcreate /dev/sda3 ... vgcreate cinder-volumes /dev/sda3 ... and so on

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Comments

1

I need to reformat the whole system to do that or I can reallocate the existing space as it is in Ubuntu? How can I do that - just a rough description?

mr_element gravatar imagemr_element ( 2014-10-30 04:28:53 -0500 )edit

resize of root partition in the place is difficult, if it is a fresh installation only for cinder I think simpler and faster just to reinstall with new partitioning.

Alex Z gravatar imageAlex Z ( 2014-10-31 05:34:15 -0500 )edit
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answered 2014-12-14 12:35:19 -0500

Nael gravatar image

In that case in a fresh installation , what would be the ideal partitioning during a fresh Ubuntu install? (what partition formats etc. ) ??

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answered 2016-02-07 21:32:52 -0500

you could just do a vgextend "cinder-volume-name" /dev/loopX on the newly created physical volume to add that space onto the existing backend as well.

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Asked: 2014-10-29 07:59:59 -0500

Seen: 4,768 times

Last updated: Apr 07 '15