Requirement of Fast Fault Detection for IP-based Network
draft-guo-ffd-requirement-00
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| Authors | Liang Guo , Yi Feng , Jizhuang Zhao , Fengwei Qin , Lily Zhao , Haibo Wang | ||
| Last updated | 2022-10-24 | ||
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draft-guo-ffd-requirement-00
Netowork Working Group L. Guo
Internet-Draft CAICT
Intended status: Informational Y. Feng
Expires: 27 April 2023 China Mobile
J. Zhao
China Telecom
F. Qin
China Mobile
L. Zhao
H. Wang
Huawei
24 October 2022
Requirement of Fast Fault Detection for IP-based Network
draft-guo-ffd-requirement-00
Abstract
The IP-based distributed system and software application layer often
use heartbeat to maintain the network topology status. However, the
heartbeat setting is long, which prolongs the system fault detection
time. This document describes the requirements for a fast fault
detection solution of IP-based network.
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."
This Internet-Draft will expire on 27 April 2023.
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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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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. IP-based NVMe . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Distributed Storage . . . . . . . . . . . . . . . . . . . 6
3.3. Cluster Computing . . . . . . . . . . . . . . . . . . . . 8
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Normative References . . . . . . . . . . . . . . . . . . 8
4.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
In the face of ever-expanding data, the powerful single-server system
cannot meet the requirements of data analysis and storage. At the
same time, with the increase of Ethernet network bandwidth and scale,
the distributed system that communicates through the network emerges
and develops rapidly. Heartbeat is a common network topology
maintenance technology used in distributed systems and software
application layers. However, if the heartbeat is set too short, the
current network congestion may lead to misjudgment. If the value of
this parameter is too long, the judgment is slow. Generally, you
need to balance and set the parameters based on various conditions.
IP-based NVMe, distributed storage and Cluster Computing are used for
core application scenarios. The requirements for performance and
impact of faults on services are increasing. This document describes
application scenarios and capability requirements for fast fault
detection in scenarios such as IP-based NVMe, artificial
intelligence, and distributed storage.
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2. Terminology
FC: Fiber Channel
NVMe: Non-Volatile Memory Express
IP-based NVMe: using RDMA or TCP to transport NVMe through Ethernet
NoF: NVMe of Fabrics
3. Use Cases
3.1. IP-based NVMe
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 include 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
operate and can be more costly than IP-based alternatives. Like FC,
InfiniBand is a lossless network requiring special hardware. IP-
based NVMe storage products tend to be more plentiful than FC-NVMe-
based options. Most storage startups focus on IP-based NVMe. But
unlink FC, The Ethernet switch 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 failover.
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+--------------------------------------+
| NVMe Host Software |
+--------------------------------------+
+--------------------------------------+
| Host Side Transport Abstraction |
+--------------------------------------+
/\ /\ /\ /\ /\
/ \ / \ / \ / \ / \
FC IB RoCE iWARP TCP
\ / \ / \ / \ / \ /
\/ \/ \/ \/ \/
+--------------------------------------+
|Controller Side Transport Abstraction |
+--------------------------------------+
+--------------------------------------+
| NVMe SubSystem |
+--------------------------------------+
Figure 1: NVMe SubSystem
This section describes the application scenarios and capability
requirements of the IP-based NVMe storage that implements fast fault
detection similar to FC.
The NVMe over RDMA or IP-based network in storage 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.
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+--+ +--+ +--+ +--+
Host |H1| |H2| |H3| |H4|
(Initiator) +/-+ +-,+ +.-+ +/-+
| | '. ,-`| |
| | `', | |
| | ,-` '. | |
+-\--+ +--`-+ +`'--+ +-\--+
| SW | | SW | | SW | | SW |
+--,-+ +---,, +,.--+ +-.--+
`. `'.,` .`
`. _,-'` ``'., .`
IP +--'`+ +`-`-+
Network | SW | | SW |
+--,,+ +,.,-+
.` `'., ,.-`` ',
.` _,-'` `.
+--`-+ +--'`+ `'---+ +-`'-+
| SW | | SW | | SW | | SW |
+-.,-+ +-..-+ +-.,-+ +-_.-+
| '. ,-` | | `., .' |
| `', | | '.` |
| ,-` '. | | ,-` `', |
Storage +-`+ `'\+ +-`+ +`'+
(Target) |S1| |S2| |S3| |S4|
+--+ +--+ +--+ +--+
Figure 2: NVMe over IP-based Network
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 when an NVMe connection is established
between the host and the storage device.
When a storage device link is faulty during running, the host cannot
detect the fault status of the indirectly connected device at the
transport layer. Based on the IP-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 fault detection and failover for IP-based NVMe.
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In this proposal, a fast fault detection solution with switch
participation is proposed. This scheme utilizes the ability of
switches to detect faults quickly at the physical layer and link
layer, and allows the switch to synchronize the detected fault
information in the IP network, and then notify the fault status to
the endpoint devices.
Fault detection procedure: The host can detect the fault status of
the storage device and quickly switch to the standby path.
1. If a storage fault occurs, the access switch detects the fault at
the storage network layer or link layer.
2. The switch synchronizes the status to other switches on the
network.
3. The switch notifies the storage fault information to the hosts.
4. Quickly disconnect the connection from the storage device and
trigger the multipathing software to switch services to the
redundant path. The fault should be detected within 1s.
+----+ +-------+ +-------+ +-------+
|Host| |Switch | |Switch | |Storage|
+----+ +-------+ +-------+ +-------+
| | |-+ |
| | |1| |
| | |-+ |
| |<----2------| |
| | | |
|<----3-------| | |
| | | |
|<----4-------|------------|-----------> |
| | | |
Figure 3: Switches interact with hosts and storage devices
3.2. Distributed Storage
Distributed storage cluster devices are interconnected through a
network (back-end IP network) to establish a cluster. When a link
fault on a node or node fault occurs in the storage cluster, other
nodes in the storage cluster cannot detect the fault status of the
indirectly connected devices through the transport layer. Based on
the IP protocol, management or master nodes in a storage cluster use
heartbeats to detect the status of storage nodes. It takes 10
seconds or more to determine whether a storage device is faulty and
switch services to another normal storage node. Services cannot be
accessed during the fault. To achieve the best customer experience
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and service reliability, we need to enhance the fault detection and
failover of IP-based cluster nodes.
Storage +--+ +--+ +--+ +--+
cluster |S1| |S2| |S3| |S4|
+--+ +--+ +--+ +--+
| '. ,-` |
| .`',_ |
| _ ..--` `'--.._ |
+-\--+ +-\--+
| SW | | SW |
+--,-+_ _+-.--+
`. `'--..._ _ .. -- '`_.`
`. _,-'` -._ .`
BACK Storage +--'`+ +`-`-+
IP Network | SW | | SW |
+----+ +----+
Figure 4: Distributed storage
The fast fault detection solution in this proposal can be used in
this scenario. This solution takes advantage of the switch's ability
to quickly detect faults at the physical layer and link layer, and
allows the switch to synchronize fault information detected on the IP
network. Then, the system notifies the storage cluster management
node or the primary node of the fault status.
Fault detection procedure:
1. If a storage fault occurs, the access switch detects the fault at
the storage network layer or link layer.
2. The switch synchronizes the status to other switches on the
network.
3. The switch notifies the storage fault information to the storage
management or master node. The fault should be detected within
1s.
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+------+ +-------+ +-------+ +-------+
|master| |Switch | |Switch | |Storage|
+------+ +-------+ +-------+ +-------+
| | |-+ |
| | |1| |
| | |-+ |
| |<----2------| |
| | | |
|<----3---------| | |
| | | |
Figure 5: Switches interact with controller
3.3. Cluster Computing
In cluster computing scenarios, for example, HPC cluster applications
and AI cluster applications, cluster node faults and failures may
occur on any node at any time. To implement cluster HA, cluster
services can be switched over from one node to another. In this
scenario, the cluster is called HA-Cluster, which does not have
obvious impact on cluster customers. The HA cluster software is used
to implement automatic fault check and service switchover. An HA
cluster with only two nodes is also called dual-system hot backup.
That is, two servers back up each other. When one server is faulty,
the other server takes over services. In this way, the system can
provide services continuously without manual intervention. Dual-
system hot backup is only a type of HA cluster. The HA cluster
system can support more than two nodes and provides more advanced
functions than dual-system hot backup to meet the changing
requirements of users. Generally, the HA cluster software can use
heartbeat+pacemaker to implement HA. The fault detection time is
longer than 30 seconds.
The fast fault detection solution in this proposal can be used in
this scenario. The switchover time can be within seconds (RTO <
min), which is the highest-level product in the disaster recovery
standard.
Fault detection procedure is similar to that of distributed storage.
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>.
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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
Liang Guo
CAICT
No.52, Hua Yuan Bei Road, Haidian District,
Beijing
100191
China
Email: guoliang1@caict.ac.cn
Yi Feng
China Mobile
12 Chegongzhuang Street, Xicheng District
Beijing
China
Email: fengyiit@chinamobile.com
Jizhuang Zhao
China Telecom
South District of Future Science and Technology in Beiqijia Town, Changping District
Beijing
China
Email: zhaojzh@chinatelecom.cn
Fengwei Qin
China Mobile
12 Chegongzhuang Street, Xicheng District
Beijing
China
Email: qinfengwei@chinamobile.com
Lily Zhao
Huawei
No. 3 Shangdi Information Road, Haidian District
Beijing
China
Email: Lily.zhao@huawei.com
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Haibo Wang
Huawei
No. 156 Beiqing Road
Beijing
P.R. China
Email: rainsword.wang@huawei.com
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