Storage Connector Charm

Overview

This charm configures a unit to connect to a storage endpoint, either iSCSI or Fibre Channel. It acts as a subordinate charm, which can be deployed on any bare metal or virtual machine, alongside a main charm. It is not supported in containers due to lack of ability for lxd containers to access iSCSI and Fibre Channel hardware of the underlying kernel.

If you configure this charm for iSCSI, this charm will:

• Generate an iSCSI initiator name and put it in /etc/iscsi/initiatorname.iscsi
• Install the package multipath-tools
• Configure multipath under /etc/multipath/conf.d directory
• Restart the services iscsid, open-iscsi
• Perform an iSCSI discovery against a target
• Login to the target
• Reload and restart the service multipathd

If you configure it for Fibre Channel, this charm will:

• Install the package multipath-tools
• Scan the host for HBA adapters
• Retrieve the WWID for the Fibre Channel connection
• Configure multipath under /etc/multipath/conf.d directory
• Reload and restart multipathd.service

Please note that the Fiber Channel option currently supports only one device.

If iSCSI, the user can input a initiator name dictionary in config.yaml if they wish to use a specific IQN for a specific unit. Also, the target IP and port are needed to perform the discovery and login with iscsiadm.

For Fibre Channel, the user can choose the device alias to be used when mapping the disk. See the option "fc-lun-alias" for further details.

Quickstart

To build the charm, use the Make actions. These actions use the charmcraft tool, so make sure to install it beforehand:

snap install charmcraft
make build

This will create the storage-connector.charm file and place it in the .build directory.

To deploy this subordinate charm on an ubuntu unit, deploy ubuntu first , or other principal charm of your choosing (i.e nova-compute, mysql, etc.).

juju add-model my-test-model
juju deploy ubuntu --series focal
juju deploy storage-connector

To configure this charm for iSCSI, do the following.

Edit the config of the target or the port:

juju config storage-connector \
    storage-type='iscsi' \
    iscsi-target=<TARGET_IP> \
    iscsi-port=<PORT>

To restart services manually, two actions exist:

juju run-action --unit ubuntu/0 restart-iscsi-services
juju run-action --unit ubuntu/0 reload-multipathd-service

To configure this charm for Fibre Channel, do the following.

Set the storage type to FC and the various configuration parameters:

juju config storage-connector storage-type='fc' \
    fc-lun-alias='data1' \
    multipath-defaults='{"user_friendly_names":"yes", "find_multipaths":"yes", "polling_interval":"10"}' \
    multipath-devices='{"vendor":"PURE", "product":"FlashArray", "fast_io_fail_tmo":"10", "path_selector":"queue-length 0", "path_grouping_policy":"group_by_prio", "rr_min_io":"1", "path_checker":"tur", "fast_io_fail_tmo":"1", "dev_loss_tmo":"infinity", "no_path_retry":"5", "failback":"immediate", "prio":"alua", "hardware_handler":"1 alua", "max_sectors_kb":"4096"}'

After the configuration is set, relate the charm to ubuntu

This will apply the configuration to hosts running the "ubuntu" application.

juju relate ubuntu storage-connector

Scaling

This charm will scale with the units it is related to. For example, if you scale the ubuntu application, and the storage-connector is related to it, it will be deployed on each newly deployed ubuntu unit.

juju add-unit ubuntu
juju remove-unit ubuntu/1

Troubleshooting

If the iSCSI discovery or login fails, compare the exit status number with the iscsiadm documentation at https://linux.die.net/man/8/iscsiadm to understand the cause of the error.

Contact

• Author: Camille Rodriguez camille.rodriguez@canonical.com
• Maintainers: BootStack Charmers bootstack-charmers@lists.canonical.com
• Issues: here