What is ISER?- a tech definition

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iSER stands for “iSCSI Extensions for RDMA”. It is an extension of the data transfer model of iSCSI, a storage networking standard for TCP/IP. It uses the iSCSI components while taking the advantage of the RDMA protocol suite.

By Tekmart Enterprise Support

ISER is an RDMA transport for iSCSI, the link protocol could be either Ethernet or InfiniBand at any supported speed (10,40,56,100Gb/s).

iSER uses the RDMA protocol suite to supply higher bandwidth for block storage transfers (zero time copy behavior). To that fact, it eliminates the TCP/IP processing overhead while preserving the compatibility with iSCSI protocol.
In addition, it has the lowest latency and lowest CPU utilization. Moreover, it enjoys the stability and benefits of the iSCSI protocol like security, high availability and so on.
Faster than iSCSI, FC, FCoE and easier to manage than SRP

Applications that can user SCSI and iSCSI layer
Network capable of passing RDMA
- Adapter cards that supports RDMA (Ethernet of InfiniBand)
- Ethernet switches (with Flow control or PFC)
- InfiniBand switches
Target that supports iSER

TGT	LIO	SCST
User space	Kernel space (in-tree)	Kernel space (out-of-tree)
iSER support since 2008	iSER support since kernel 3.10	iSER support since 2014
Linux SCSI target framework (tgt) project	Linux SCSI Target	SCST: A Generic SCSI Target Subsystem for Linux

Storage Protocol	iSER (iSCSI RDMA)	iSCSI (TCP)	FC	FCoE	SMB Direct	NFSoRDMA	NVMe over Fabrics
Access	Block	Block	Block	Block	File	File	Block
Transport (link protocol)	Ethernet (RoCE), InfiniBand	Ethernet	FC	Ethernet	Ethernet (RoCE), InfiniBand	Ethernet (RoCE), InfiniBand	Ethernet (RoCE), InfiniBand
RDMA	Yes	No	No	No	Yes	Yes	Yes

iSER based on TGT target is inbox in OpenStack since Havana release.

iSER data mover for OpenStack accelerates:

The transport layer iSER and/or iSCSI/TCP are transparent to the user. The configuration is simple.