Mellanox-Cinder

= Overview = Mellanox added iSCSI Extensions for RDMA (iSER) that does not need the TCP layer. Therefore, it provides lower latency and higher performance.

It permits data to be transferred directly into and out of SCSI computer memory buffers, which connects computers to storage devices, without intermediate data copies.

iSER is a server network protocol that extends the Internet Small Computer System Interface (iSCSI) protocol to use Remote Direct Memory Access (RDMA).

Please contact Mellanox for further information and benchmark results.

Installation
Provisioned through standard Cinder installation.

Configuration
In order to enable iSER, adjust these values at /etc/cinder/cinder.conf:

iscsi_ip_address =  iscsi_protocol = iser volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver

iscsi_ip_address is required to do a "discovery" over the IB/RoCE interface from the initiator side.

volume_driver points cinder to use the LVMVolumeDriver.

Restart Cinder service


 * 1) /etc/init.d/openstack-cinder-volume restart

For troubleshooting issues, refer to section Known Issues

= Known Issues =

(1) “scsi-target-utils” package:

Note: For RH6.4 or below, “scsi-target-utils” package version needs to be 1.0.38 and above. If you use RDO installation, you should check the version. The RPM can be found at http://www.mellanox.com/downloads/solutions/rpms/
 * 1) wget http://www.mellanox.com/downloads/solutions/rpms/scsi-target-utils-1.0.39-v1.0.39.c1135a.x86_64.rpm
 * 2) rpm -Uvh scsi-target-utils-1.0.39-v1.0.39.c1135a.x86_64.rpm

In addition, RH6.5 includes “scsi-target-utils” package with version 1.0.24-10. This version number is sufficient and no further action is needed for RHEL6.5.

(2) Using old versions of Openstack (Havana release or lower), boot Instance from volume fails when iSER is enabled:

Steps to reproduce the bug:

- Create new volume with image source.

- Launch a new instance boot from the above volume using iSER transport.

The bug is defined here: 

A patch can be found here:

To apply the patch, run the following commands on all nova-compute nodes:
 * 1) wget http://www.mellanox.com/downloads/solutions/openstack/havana/patches/volume.patch
 * 2) patch -p1 < volume.patch
 * 3) service nova-compute restart

(3) Flow control:

In case the network is Ethernet, make sure that flow control is enabled on the switches on the relevant ports across the network.

(4) Linux-IO (LIO) support limitation:

Open-source implementation of SCSI target in Openstack can be managed by either TGT or LIO.

In Openstack, iSER is supported over TGT only until the Kilo version, and iSER support over LIO is available from the Kilo release.

Please use iscsi_helper parameter to specify the ISCSI target type (for more details, please follow: Cinder editional options).

= References = 1. LVM driver documentation

2. OpenStack solution page at Mellanox site

3. Legacy source repository

4. Mellanox OFED web page

5. Cinder-controller for Havana

6. Cinder-node for Havana

Return to Mellanox-OpenStack wiki page.

For more details, please direct any inquiries to [mailto:openstack@mellanox.com openstack@mellanox.com].