Cinder is the default block storage service on Openstack. Cinder service manages the volumes , volume snapshots, and volume types. Prior to year 2012 , cinder was part of nova module in the name of nova-volume. To reduce the nova coding and improve the volume service, developers has separated the volume service from nova codes and they named volume service as cinder. Since then , multiple vendors are started providing the API to the cinder services. By default , cinder uses the LVM as back-end storage system. The default configuration file is /etc/cinder/cinder.conf. In this article, I will demonstrate that how to use the cinder service on Openstack which is configured using devstack method.
There are three important components in cinder block service.
- cinder-volume.
- cinder-scheduler
- cinder-backup
- Messaging queue. (RabbitMQ)
Cinder act like a front-end interface and communicate to LVM or Ceph using the API in the back-end to provide the volume services. Ceph is the advanced storage which eliminates the limitations of LVM.
Note: In my case, both Openstack controller node & cinder nodes are same. Created this environment using the devstack method on Ubuntu.
Configure the cinder: (Only for the testing purpose )
Note: Since I have logged in as stack user , Need to use sudo command to get the necessary privileges.
1.Let’s have dedicated harddrive for cinder.
stack@uacloud:~$ sudo fdisk -l /dev/sdb Disk /dev/sdb: 10.7 GB, 10737418240 bytes 255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sdb doesn't contain a valid partition table stack@uacloud:~$
2. Install the lvm2 packages. (In my case, lvm2 is already installed)
stack@uacloud:~$ sudo apt-get install lvm2 Reading package lists... Done Building dependency tree Reading state information... Done lvm2 is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 17 not upgraded. stack@uacloud:~$
3. Create the physical volume using the /dev/sdb.
stack@uacloud:~$ sudo pvcreate /dev/sdb Physical volume "/dev/sdb" successfully created stack@uacloud:~$ stack@uacloud:~$ sudo pvs PV VG Fmt Attr PSize PFree /dev/loop0 stack-volumes-lvmdriver-1 lvm2 a-- 10.01g 10.01g /dev/sdb lvm2 a-- 10.00g 10.00g stack@uacloud:~$
4. Create the volume group using /dev/sdb.
stack@uacloud:~$ sudo vgcreate stack-vg /dev/sdb Volume group "stack-vg" successfully created stack@uacloud:~$ sudo vgs VG #PV #LV #SN Attr VSize VFree stack-vg 1 0 0 wz--n- 10.00g 10.00g stack-volumes-lvmdriver-1 1 0 0 wz--n- 10.01g 10.01g stack@uacloud:~$
5. Edit the cinder.conf like below. Just replaced volume group name as stack-vg.
stack@uacloud:~$ cat /etc/cinder/cinder.conf |grep group volume_group = stack-volumes-lvmdriver-1 stack@uacloud:~$ cp /etc/cinder/cinder.conf /etc/cinder/cinder.conf.08092015 stack@uacloud:~$ vi /etc/cinder/cinder.conf stack@uacloud:~$ cat /etc/cinder/cinder.conf |grep group volume_group = stack-vg stack@uacloud:~$
6. Run unstack.sh & re-join.sh to restart all the openstack services.
stack@uacloud:~/devstack$ ./unstack.sh Site keystone disabled. To activate the new configuration, you need to run: service apache2 reload * Stopping web server apache2 * * Starting web server apache2 AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1. Set the 'ServerName' directive globally to suppress this message * pkill: killing pid 42051 failed: Operation not permitted pkill: killing pid 42055 failed: Operation not permitted * Stopping web server apache2 * tgt stop/waiting stack@uacloud:~/devstack$ ./rejoin-stack.sh [detached from 48132.stack] stack@uacloud:~/devstack$
8. Login to Openstack Dashboard to use the first cinder volume. If you unable to get the Dashboard, restart the Apache services like below.
stack@uacloud:~/devstack$ sudo service apache2 restart * Restarting web server apache2 [ OK ] stack@uacloud:~/devstack$
9. By default, nova instance creates the image file under below mentioned location when you launch the instance (using image).
stack@uacloud:~$ cd data/nova/instances/ stack@uacloud:~/data/nova/instances$ ls -lrt total 16 -rw-rw-r-- 1 stack stack 30 Sep 8 21:56 compute_nodes drwxrwxr-x 2 stack stack 4096 Sep 8 22:34 locks drwxrwxr-x 2 stack stack 4096 Sep 8 22:34 _base drwxrwxr-x 2 stack stack 4096 Sep 8 22:34 cb52c5ac-869f-498c-8457-d0204b8cb756 stack@uacloud:~/data/nova/instances$ cd cb52c5ac-869f-498c-8457-d0204b8cb756/ stack@uacloud:~/data/nova/instances/cb52c5ac-869f-498c-8457-d0204b8cb756$ ls -lrt total 19056 -rw-rw-r-- 1 root root 4969360 Sep 8 22:34 kernel -rw-rw-r-- 1 root root 3723817 Sep 8 22:34 ramdisk -rw-rw-r-- 1 root root 419840 Sep 8 22:34 disk.config -rw-r--r-- 1 stack stack 347 Sep 8 22:34 disk.info -rw-rw-r-- 1 stack stack 2920 Sep 8 22:34 libvirt.xml -rw-rw---- 1 root root 17283 Sep 8 22:34 console.log -rw-r--r-- 1 root root 10420224 Sep 8 22:35 disk stack@uacloud:~/data/nova/instances/cb52c5ac-869f-498c-8457-d0204b8cb756$
10. Since we have configured the cinder , Let’s create new instance on cinder volume. Login to the Openstack dashboard & Launch instance.
11. Click on Access & security to map the right key pairs & security profile.
12. Here you can see that instance has been created using the cinder volume.
13. Navigate to the volumes tab. Here you can see that volume is created and attached to the instance “vua02”. Since it is a OS volume , so marked as bootable. (Right side)
There was an issue while configuring the cinder service where I am unable to create a new volume using the dashboard. But I was able to create the volume using “cinder create 1” using command line. To fix this , I have re-installed the ISCSI packages. (Ubuntu)
# apt-get install iscsitarget-dkms --reinstall # apt-get install iscsitarget --reinstall
14. Let’s see how it has been created in the back-end. List the cinder volume .
stack@uacloud:~/devstack$ cinder list +--------------------------------------+--------+------+------+-------------+----------+--------------------------------------+ | ID | Status | Name | Size | Volume Type | Bootable | Attached to | +--------------------------------------+--------+------+------+-------------+----------+--------------------------------------+ | e7b408ee-96dd-4453-9e0e-3086a694a652 | in-use | | 1 | lvmdriver-1 | true | de53f0a5-f8a0-4c43-85f6-8cdd0c169134 | +--------------------------------------+--------+------+------+-------------+----------+--------------------------------------+ stack@uacloud:~/devstack$
In the back-end , cinder service communicates to the LVM driver & create the volumes on the specified volume group (Refer Step 5).
stack@uacloud:~/devstack$ sudo lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert volume-e7b408ee-96dd-4453-9e0e-3086a694a652 cinder-volumes -wi-ao--- 1.00g stack@uacloud:~/devstack$
Hope this article is informative to you.