[翻译]iser是什么?

iser是什么?
翻译自:https://community.mellanox.com/docs/DOC-1466
参考:

• What is RDMA?
• HowTo Configure TGT enabled with iSER Transport for RHEL
• HowTo Configure TGT enabled with iSER Transport for Ubuntu
• HowTo Configure LIO enabled with ISER for RHEL7 Inbox Driver
• HowTo Configure LIO enabled with ISER for Ubuntu 14.04 Inbox driver
• HowTo Configure SCST Block Storage Target Enabled with ISER

• External storage solution for HP ProLiant Moonshot Servers via iSCSI

• Feature-based Comparison of iSCSI Target implementations
• RFC 7145 - iSCSI Extensions for RDMA

本文适用于那些想弄明白InfiniBand/RDMA/ISER是什么的新手,以及使用InfiniBand/RDMA/ISER的优势有哪些?

iser是什么?
iser代表"iSCSI Extensions for RDMA".iser是数据传输规范iscsi(一个适用于TCP/IP的存储网络标准)的一个扩展.
iser使用了iscsi组件,同时也有rdma套件(suite)的优势.

iser的link protocol是什么?
iser基于iscsi的rdma传输,link protocol可以是任何受到支持的速度(10,40,56,100Gb/s)的Ethernet 或者Infiniband/

iser的优势有哪些?
1.iser使用rdma套件(suite)来为块存储传输(block storage transfers)提供高带宽(zero time copy behavior).
  基于这一事实,iser消除了tcp/ip 处理过载同时保证了对iscsi协议的兼容性.

2.除此之外,iser有最低的延迟和最低的cpu使用.此外,iser 有iscsi协议的稳定性和益处,比如安全,高可用等等.
3.比iscsi,fc,fcoe都要快,比srp更容易管理.

部署iser需要满足什么要求?
1.使用scsi和iscsi层的应用程序
2.passing rmda的网络兼容性
  2.1支持rdma的Adapter cards(Ethernet of InfiniBand)---译者注:估计是Ethernet or InfiniBand
  2.2以太网交换机(带flow control or PFC)
  2.3InfiniBand 交换机
3.支持iser的target



哪些存储target支持iser?
1.Linux targets:
  1.1 Linux IO(LIO) 
  1.2 Linux iSCSI target framework (TGT)
  1.3 Generic SCSI target subsystem for Linux (SCST)
2.Oracle ZFS, Violin Memory, Zadara Saratoga Speed, HP SL4540 Moonshot server and other tailored storage targets.

• Configuring SAN iSER Targets - Oracle® ZFS Storage Appliance Administration Guide, Release 2013.1.3.0
• http://www.violin-memory.com/wp-content/uploads/resources/Violin_Memory_Interoperability_Best_Practices.pdf
• https://www.zadarastorage.com/accelerating-storage-iscsi-extensions-for-rdma/
• http://www.ethernetsummit.com/English/Collaterals/Proceedings/2015/20150415_1B_Crupnicoff.pdf
• http://h20195.www2.hp.com/V2/getpdf.aspx/4AA5-5656ENW.pdf

TGT, LIO , SCST这三者的区别?
TGTLIOSCSTUser spaceKernel space (in-tree)Kernel space (out-of-tree)iSER support since 2008iSER support since kernel 3.10iSER support since 2014Linux SCSI target framework (tgt) projectLinux SCSI TargetSCST: A Generic SCSI Target Subsystem for Linux

Link Protocol/Transport Comparison

Storage Protocol Comparison

Storage ProtocoliSER (iSCSI RDMA)iSCSI (TCP)FCFCoESMB DirectNFSoRDMANVMe over FabricsAccessBlockBlockBlockBlockFileFileBlockTransport (link protocol)Ethernet (RoCE), InfiniBandEthernetFCEthernetEthernet (RoCE), InfiniBandEthernet (RoCE), InfiniBandEthernet (RoCE), InfiniBandRDMAYesNoNoNoYesYesYes

OpenStack Support
iSER based on TGT target is inbox in OpenStack since Havana release.
iSER data mover for OpenStack accelerates:
  Storage access
  VM migration
  Data/VM replication


iSCSI/iSER Architecture

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