What is LIO target? Linux-OI Target is a Linux SCSI target introduced in a kernel v.2.6.38 and supports different fabrics modules like FibreChannel, iSCSI, iSER, etc. It works in a kernel space, so it’s faster than tgtd which is used in Cinder by default. Why do we still use tgtd instead of more faster LIO in Cinder by default? It’s only because we have to support rolling upgrades and we don’t know how to migrate from TGTd to LIO in a such way and pass Grenade successfully.
We’ve got non-voting gate-tempest-dsvm-full-lio-ubuntu-xenial job for a while. Due to some of my performance tests results it’s really faster than tgtd. So, how can you use it?
It’s pretty easy with LVM + Devstack. Everything you need is to add ‘CINDER_ISCSI_HELPER=lioadm’ to your localrc/local.conf.
If you have already configured Cinder+LVM it’s easy too to switch to the new target driver. I mean that you don’t have any in-use volume now but you have Cinder with LVM configured and running. Just follow these steps:
1) first of all, you have to install ‘rtslib-fb’ package using pip:
# pip install rtslib-fb
or using OS package manager:
# apt-get install python-rtslib-fb
2) stop tgt:
# sudo service tgt stop
3) change /etc/cinder/cinder.conf to use LIO driver:
Set ‘iscsi_helper = lioadm’ instead of ‘iscsi_helper = tgtadm’
4) restart cinder and enjoy it!