Performance Implications Libiscsi RDMA Support

Storage virtualization is gaining popularity as an efficient way to increase the flexibility and the consolidation of data centers. Virtualization is commonly used to provide fast and reliable storage access and therefore constitute an important factor to fulfill customer’s demand for a minimum latency in cloud storage applications. This work introduces a new approach for implementing the iSCSI extensions for RDMA protocol (iSER) using block virtualization techniques. The iSER protocol is implemented in the user-space using the common Libiscsi library and serve as the transportation layer protocol instead of the common TCP protocol. A unique implementation of a virtual block device using Quick Emulator (QEMU) is proposed to carry out block virtualization delivered over iSCSI. The benefit of using iSCSI/iSER protocol over the common iSCSI/TCP is clearly demonstrated. Experiments results demonstrate average improvement factor of about 200% over the common iSCSI/TCP in term of average I/O operations per second while using the conventional Flexible I/O storage benchmark. The proposed approach is compared to two commonly iSER implementations used for block virtualization. Both methods use common iSER kernel modules. The first method uses a virtual-function while the second technique uses iSER block device virtualization. The proposed user-space iSER approach shows significant performance improvement over the two existing methods for different typical workloads. The current research results are promising and applicable also to future upcoming protocols such as NVMe over Fabrics implementations. Learning Objectives Storage virtalization RDMA iSER QEMU