NVMe over Fabric Network Requirement
draft-guo-nof-requirement-00
The information below is for an old version of the document.
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|---|---|---|---|
| Authors | Liang Guo , Yi Feng , Jizhuang Zhao , Lily Zhao , Haibo Wang | ||
| Last updated | 2022-03-07 | ||
| Replaced by | draft-guo-ffd-requirement | ||
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draft-guo-nof-requirement-00
Netowork Working Group L. Guo
Internet-Draft CAICT
Intended status: Experimental Y. Feng
Expires: 8 September 2022 China Mobile
J. Zhao
China Telecom
L. Zhao
H. Wang
Huawei
7 March 2022
NVMe over Fabric Network Requirement
draft-guo-nof-requirement-00
Abstract
NVMe over Fabrics defines a common architecture that supports a range
of storage networking fabrics for NVMe block storage protocol over a
storage networking fabric, such as Ethernet, Fibre Channel and
InfiniBand. For Ethernet-based network, RDMA or TCP technology can
be used to transport NVMe, but the network management mechanism is
simple, and fault detection is weak.
This document describes the solution requirements for automatic
device discovery to improve usability and quick switchover to improve
reliability.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 8 September 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use Case . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Normative References . . . . . . . . . . . . . . . . . . 7
4.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
For a long time, the key storage applications and high performance
requirements are mainly based on FC networks. With the increase of
transmission rates, the medium has evolved from HDDs to solid-state
storage, and the protocol has evolved from SATA to NVMe. The
emergence of new NVMe technologies brings new opportunities. With
the development of the NVMe protocol, the application scenario of the
NVMe protocol is extended from PCIe to other fabrics, solving the
problem of NVMe extension and transmission distance. The block
storage protocol uses NoF to replace SCSI, reducing the number of
protocol interactions from application hosts to storage systems. The
end-to-end NVMe protocol greatly improves performance.
Fabrics of NoF includes Ethernet, Fibre Channel and InfiniBand.
Comparing FC-NVMe to Ethernet- or InfiniBand-based Network
alternatives generally takes into consideration the advantages and
disadvantages of the networking technologies. Fibre Channel fabrics
are noted for their lossless data transmission, predictable and
consistent performance, and reliability. Large enterprises tend to
favor FC storage for mission-critical workloads. But Fibre Channel
requires special equipment and storage networking expertise to
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operate and can be more costly than Ethernet-based alternatives.
Like FC, InfiniBand is a lossless network requiring special hardware.
Ethernet-based NVMe storage products tend to be more plentiful than
FC-NVMe-based options. Most storage startups focus on Ethernet-based
NVMe. But unlike FC, InfiniBand and Ethernet lack a discovery
service that enables the automatic addition of nodes to the fabric.
And unlink FC, The Ethernet switch does not have zone management and
does not notify the Change of device status. When the device is
faulty, relying on the NVMe link heartbeat message mechanism , the
host takes tens of seconds to complete service switchover.
+--------------------------------------+
| NVMe Host Software |
+--------------------------------------+
+--------------------------------------+
| Host Side Transport Abstraction |
+--------------------------------------+
/\ /\ /\ /\ /\
/ \ / \ / \ / \ / \
FC IB RoCE iWARP TCP
\ / \ / \ / \ / \ /
\/ \/ \/ \/ \/
+--------------------------------------+
|Controller Side Transport Abstraction |
+--------------------------------------+
+--------------------------------------+
| NVMe SubSystem |
+--------------------------------------+
This document describes the application scenarios and capability
requirements of the Ethernet-based NVMe that implements automatic
device discovery, domain management, and fault notification similar
to FC.
2. Terminology
Ethernet-based NVMe: using RDMA or TCP to transport NVMe through
Ethernet
FC: Fiber Channel
NVMe: Non-Volatile Memory Express
NoF: NVMe of Fabrics
CDC: Centralized Discovery Controller
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3. Use Case
The NVMe over RDMA or TCP Ethernet-based network in storage is as
follows, the network mainly includes three types of roles: an
initiator (referred to as a host), a switch, and a target (referred
to as a storage device). Initiators and targets are also referred to
as endpoint devices. Hosts and storage devices use the Ethernet-
based NVMe to transmit data over the network to provide high
performance storage services.
+--+ +--+ +--+ +--+
Host |H1| |H2| |H3| |H4|
(Initiator) +/-+ +-,+ +.-+ +/-+
| | '. ,-`| |
| | `', | |
| | ,-` '. | |
+-\--+ +--`-+ +`'--+ +-\--+
| SW | | SW | | SW | | SW |
+--,-+ +---,, +,.--+ +-.--+
`. `'.,` .`
`. _,-'` ``'., .`
Internet +--'`+ +`-`-+
Network | SW | | SW |
+--,,+ +,.,-+
.` `'., ,.-`` ',
.` _,-'` `.
+--`-+ +--'`+ `'---+ +-`'-+
| SW | | SW | | SW | | SW |
+-.,-+ +-..-+ +-.,-+ +-_.-+
| '. ,-` | | `., .' |
| `', | | '.` |
| ,-` '. | | ,-` `', |
Storage +-`+ `'\+ +-`+ +`'+
(Target) |S1| |S2| |S3| |S4|
+--+ +--+ +--+ +--+
Sub-Scenario 1: Initial Deployment
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During initial system deployment, hosts and storage devices are
connected to the network separately and In order to achieve high
reliability, each host and storage device are connected to dual
network planes simultaneously. The host can read and write data
services only when an NVMe connection is established between the host
and the storage device. To establish an NVMe connection, the host
need to know the IP address of the storage device. However,
Ethernet-based NVMe lacks a discovery service and cannot detect the
status of access devices, manual configuration of storage IP
addresses is required on host. Manual configuration is complex and
error-prone.
Sub-Scenario 2: Expansion During expansion, hosts or storage devices
need to be added. The problem is the same as that in sub-scenario 1.
When a new host is mounted to a storage device, you need to manually
configure the storage device, which is complex too.
Sub-scenario 3: Storage Faults When a storage device is faulty during
running, no device proactively notifies the host of the fault status.
Based on the Ethernet-based NVMe protocol, the host uses the NVMe
heartbeat to detect the status of the storage device. The heartbeat
message interval is 5s. Therefore, it takes tens of seconds to
determine whether the storage device is faulty and perform service
switchover using the multipath software. Failure tolerance time for
core applications cannot be reached. In order to obtain the best
customer experience and business reliability requirement, we need to
enhance the Ethernet-based NVMe, supports automatic device discovery
and fault status notification. In the CDC(Centralized Discovery
Controller) solution being discussed by NVMe organizations, hosts and
storage devices report device information to the CDC, and the CDC
synchronizes the information to the host. The host establishes an
NVMe link to implement automatic device discovery. However, the CDC
solution does not involve fault status notification. Therefore, the
system cannot notify a fault status of a device, and the failover
time is still long. For core services, the duration of service
impact is critical.
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The solution proposed in this document is similar to the FC-NVMe
system. The switch functions as the manager of the entire network,
manages device information and status, and synchronizes information
between switches on the entire network. In addition, to isolate
storage services securely, a concept similar to a zone on a Fibre
Channel network is introduced. Hosts and storage devices are planned
in a zone and NVMe links can be established between the hosts and
storage devices in the zone. The detailed requirements for hosts,
switches, and storage devices on the network are as follows:
Automatic device discovery: When a storage device is connected to a
network, the host can automatically discover the storage device and
establish an NVMe connection.
1. When the host accesses the network, the device access information
is sent to the switch periodically. When the storage device is
connected to the network, the device access information is sent
to the switch periodically.
2. After receiving the host and storage access information, the
switch synchronizes the information to other switches.
3. The switch identifies objects in the same zone and synchronizes
host and storage device information to objects in the zone.
4. After receiving the storage device information provided by the
switch, the host automatically establishes an NVMe connection.
+----+ +-------+ +-------+ +-------+
|Host| |Storage| |Switch | |Switch |
+----+ +-------+ +-------+ +-------+
| | | |
|-----1------>| | |
| |-----1----->| |
| | |-----2------>|
| | | |
| | |<----2-------|
| | | |
|<----3-------|-----3------| |
| | | |
|-----4------>| | |
| | | |
| | | |
Fault detection: The host can detect the fault status of the storage
device and quickly switch to the standby path.
1. The host subscribes to the storage status information from the
switch.
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2. If a storage fault occurs, the access switch detects the fault at
the storage network layer or link layer.
3. The switch synchronizes the status to other switches on the
network.
4. The switch identifies the hosts that subscribe to the storage
status in the zone and synchronizes the storage fault information
to the hosts.
5. Quickly disconnect the connection from the storage device and
trigger the multipathing software to switch services to the
redundant path. The fault is detected within 1s.
+----+ +-------+ +-------+ +-------+
|Host| |Storage| |Switch | |Switch |
+----+ +-------+ +-------+ +-------+
| | | |
|-----1-------|----------->| |
| | |-+ |
| | |2| |
| | |-+ |
| | | |
| | |<----3-------|
|<----4-------|------------| |
| | | |
|-----4------>| | |
| | | |
| | | |
4. References
4.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
4.2. Informative References
[ODCC-2020-05016]
Open Data Center Committe, "NVMe over RoCEv2 Network
Control Optimization Technical Requirements and Test
Specifications", 2020.
Authors' Addresses
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Liang Guo
CAICT
No.52, Hua Yuan Bei Road, Haidian District,
Beijing
Beijing, 100191
China
Email: guoliang1@caict.ac.cn
Yi Feng
China Mobile
12 Chegongzhuang Street, Xicheng District
Beijing
Beijing,
China
Email: yangzhiyong@chinamobile.com
Jizhuang Zhao
China Telecom
South District of Future Science and Technology in Beiqijia Town, Changping District
Beijing
Beijing,
China
Email: zhaojzh@chinatelecom.cn
Lily Zhao
Huawei
No. 3 Shangdi Information Road, Haidian District
Beijing
Beijing,
China
Email: Lily.zhao@huawei.com
Haibo Wang
Huawei
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: rainsword.wang@huawei.com
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