.. _cinder-guide: ====================== Cinder - Block storage ====================== Overview ~~~~~~~~ Cinder can be deployed using Kolla and supports the following storage backends: * ceph * hnas_iscsi * hnas_nfs * iscsi * lvm * nfs LVM ~~~ When using the ``lvm`` backend, a volume group should be created on each storage node. This can either be a real physical volume or a loopback mounted file for development. Use ``pvcreate`` and ``vgcreate`` to create the volume group. For example with the devices ``/dev/sdb`` and ``/dev/sdc``: .. code-block:: console pvcreate /dev/sdb /dev/sdc vgcreate cinder-volumes /dev/sdb /dev/sdc During development, it may be desirable to use file backed block storage. It is possible to use a file and mount it as a block device via the loopback system. .. code-block:: console free_device=$(losetup -f) fallocate -l 20G /var/lib/cinder_data.img losetup $free_device /var/lib/cinder_data.img pvcreate $free_device vgcreate cinder-volumes $free_device Enable the ``lvm`` backend in ``/etc/kolla/globals.yml``: .. code-block:: yaml enable_cinder_backend_lvm: "yes" .. note:: There are currently issues using the LVM backend in a multi-controller setup, see `_bug 1571211 `__ for more info. NFS ~~~ To use the ``nfs`` backend, configure ``/etc/exports`` to contain the mount where the volumes are to be stored: .. code-block:: console /kolla_nfs 192.168.5.0/24(rw,sync,no_root_squash) In this example, ``/kolla_nfs`` is the directory on the storage node which will be ``nfs`` mounted, ``192.168.5.0/24`` is the storage network, and ``rw,sync,no_root_squash`` means make the share read-write, synchronous, and prevent remote root users from having access to all files. Then start ``nfsd``: .. code-block:: console systemctl start nfs On the deploy node, create ``/etc/kolla/config/nfs_shares`` with an entry for each storage node: .. code-block:: console storage01:/kolla_nfs storage02:/kolla_nfs Finally, enable the ``nfs`` backend in ``/etc/kolla/globals.yml``: .. code-block:: yaml enable_cinder_backend_nfs: "yes" Validation ~~~~~~~~~~ Create a volume as follows: .. code-block:: console openstack volume create --size 1 steak_volume Verify it is available. If it says "error", then something went wrong during LVM creation of the volume. .. code-block:: console openstack volume list +--------------------------------------+--------------+-----------+------+-------------+ | ID | Display Name | Status | Size | Attached to | +--------------------------------------+--------------+-----------+------+-------------+ | 0069c17e-8a60-445a-b7f0-383a8b89f87e | steak_volume | available | 1 | | +--------------------------------------+--------------+-----------+------+-------------+ Attach the volume to a server using: .. code-block:: console openstack server add volume steak_server 0069c17e-8a60-445a-b7f0-383a8b89f87e Check the console log to verify the disk addition: .. code-block:: console openstack console log show steak_server A ``/dev/vdb`` should appear in the console log, at least when booting cirros. If the disk stays in the available state, something went wrong during the iSCSI mounting of the volume to the guest VM. Cinder LVM2 backend with iSCSI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As of Newton-1 milestone, Kolla supports LVM2 as cinder backend. It is accomplished by introducing two new containers ``tgtd`` and ``iscsid``. ``tgtd`` container serves as a bridge between cinder-volume process and a server hosting Logical Volume Groups (LVG). ``iscsid`` container serves as a bridge between nova-compute process and the server hosting LVG. In order to use Cinder's LVM backend, a LVG named ``cinder-volumes`` should exist on the server and following parameter must be specified in ``globals.yml``: .. code-block:: yaml enable_cinder_backend_lvm: "yes" For Ubuntu and LVM2/iSCSI ------------------------- ``iscsd`` process uses configfs which is normally mounted at ``/sys/kernel/config`` to store discovered targets information, on centos/rhel type of systems this special file system gets mounted automatically, which is not the case on debian/ubuntu. Since ``iscsid`` container runs on every nova compute node, the following steps must be completed on every Ubuntu server targeted for nova compute role. - Add configfs module to ``/etc/modules`` - Rebuild initramfs using: ``update-initramfs -u`` command - Stop ``open-iscsi`` system service due to its conflicts with iscsid container. Ubuntu 16.04 (systemd): ``systemctl stop open-iscsi; systemctl stop iscsid`` - Make sure configfs gets mounted during a server boot up process. There are multiple ways to accomplish it, one example: .. code-block:: console mount -t configfs /etc/rc.local /sys/kernel/config .. note:: There is currently an issue with the folder /sys/kernel/config as it is either empty or does not exist in several operating systems, see `_bug 1631072 `__ for more info Cinder backend with external iSCSI storage ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In order to use external storage system (like the ones from EMC or NetApp) the following parameter must be specified in ``globals.yml``: .. code-block:: yaml enable_cinder_backend_iscsi: "yes" Also ``enable_cinder_backend_lvm`` should be set to ``no`` in this case.