Internet DRAFT - draft-nof-framework
draft-nof-framework
Network Working Group H. Wang
Internet-Draft L. Zhao
Intended status: Standards Track S. Chen
Expires: 8 September 2022 Huawei
7 March 2022
NVMe over Fabric Network Framework
draft-nof-framework-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 networks, RDMA or TCP technology can
be used to transport NVMe, but the network management mechanism is
simple, and fault detection is weak.
This document defines the architecture of the Ethernet-based NVMe
control optimization technology, including service processes between
hosts, storage devices and network switches, and fast fault-aware
switchover.
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
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 8 September 2022.
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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
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Reference Models . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Basic Model . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. CLOS Model . . . . . . . . . . . . . . . . . . . . . . . 4
4. Functional Components . . . . . . . . . . . . . . . . . . . . 5
4.1. Storage Device . . . . . . . . . . . . . . . . . . . . . 5
4.2. Host . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.3. Network Device . . . . . . . . . . . . . . . . . . . . . 6
5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. IP Domain Management . . . . . . . . . . . . . . . . . . 7
5.2. Network Deployment . . . . . . . . . . . . . . . . . . . 8
5.3. Storage and Host Access . . . . . . . . . . . . . . . . . 9
5.4. NoF Information Advertisement . . . . . . . . . . . . . . 9
6. Reliability Consider . . . . . . . . . . . . . . . . . . . . 10
6.1. Storage Failure . . . . . . . . . . . . . . . . . . . . . 10
6.2. Host Failure . . . . . . . . . . . . . . . . . . . . . . 10
6.3. Access Link Failure . . . . . . . . . . . . . . . . . . . 10
6.4. Network Link Failure . . . . . . . . . . . . . . . . . . 10
6.5. Network Device Failure . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . . 11
10.2. References . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
For a long time, the key storage applications and high performance
requirements were 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 SCSI to NVMe. The
emergence of new NVMe technologies brings new opportunities.
Ethernet-based NVMe is an implementation of NVMe over Fabric that
best fits NVMe semantics. It surpasses FC in terms of performance,
cost and network management. It is the development trend of high-
speed storage networks in the future. Ethernet-based NVMe has been
defined in NVM Express. The specification defined in this document
optimizes network control in terms of ease of use, maintainability,
and reliability, making Ethernet-based NVMe more suitable for high
reliability requirements of key applications. This feature improves
system usability and maintainability.
The [ODCC-2020-05016] defined the basic specifications for NVME of
RoCEv2, and this document draws on that definition.
2. Terminology
NoF : NVMe of Fabric
FC : Fiber Channel
NVMe : Non-Volatile Memory Express
3. Reference Models
An Ethernet-based NVMe 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 protocol to transmit data over the network to
provide high-performance storage services.
3.1. Basic Model
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+--+ +--+
Host |H1| |H2|
(Initiator) +-,+ +_.+
| `', _-` |
| _-` |
| _-` `', |
Ethernet +----+ +----+
Network | SW | | SW |
+---,+ +_.--+
| `', _-` |
| `', |
| _-` `', |
Storage +-`+ +`'+
(Target) |S1| |S2|
+--+ +--+
Figure 1 : Basic Model
This is the basic model for small-scale storage access networks.
Hosts and storage devices are dual-homed to different switches.
After a host or a storage device is connected to a switch, they
register their information to the switch and obtain registration
information of other hosts/storage devices from the switch node.
3.2. CLOS Model
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+--+ +--+ +--+ +--+
Host |H1| |H2| |H3| |H4|
(Initiator) +/-+ +-,+ +.-+ +/-+
| | '. ,-`| |
| | `', | |
| | ,-` '. | |
+-\--+ +--`-+ +`'--+ +-\--+
| SW | | SW | | SW | | SW |
+--,-+ +---,, +,.--+ +-.--+
`. `'.,` .`
`. _,-'` ``'., .`
Ethernet +--'`+ +`-`-+
Network | SW | | SW |
+--,,+ +,.,-+
.` `'., ,.-`` ',
.` _,-'` `.
+--`-+ +--'`+ `'---+ +-`'-+
| SW | | SW | | SW | | SW |
+-.,-+ +-..-+ +-.,-+ +-_.-+
| '. ,-` | | `., .' |
| `', | | '.` |
| ,-` '. | | ,-` `', |
Storage +-`+ `'\+ +-`+ +`'+
(Target) |S1| |S2| |S3| |S4|
+--+ +--+ +--+ +--+
Figure 2 : CLOS Model
This is a relatively large-scale storage network which applies to a
large-scale storage device access network.
Hosts and storage nodes connect to different switch nodes and
register to the switch nodes. The switch needs to flood the
registration information received locally to other switch nodes on
the network.
4. Functional Components
The Ethernet-based NVMe network consists of storage devices, hosts
and switches.
4.1. Storage Device
As the server side, storage devices provide storage access services
for hosts. When a storage device is connected to a switch, storage
service information must be registered and periodically notified to
the switch to ensure the validity of information.
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If the storage device has interest in information of other storage
device or host in the storage network, it may also receive the
notification of such information from the switch.
+-------+ +------+
|Storage| |Switch|
+-------+ +------+
| Register Msg |
| ----------------------->|
| |
| Notification Msg |
| <-----------------------|
| |
| |
Figure 3 : Storage Device
4.2. Host
The host is the client of the storage device. When a host accesses a
switch, it needs to register the host information to the switch and
periodically publish it.
As the client side, a host needs to quickly obtain the service status
of the storage device that provides services. When the host obtains
the notification message from the switch indicating that the storage
device goes online, the host may establish a connection to the
storage device. When the host receives a notification message from
the switch indicating that the storage device is faulty, the host
needs to quickly disconnect from the storage device and attempt to
establish a connection to other redundant storage devices.
+-------+ +------+
| HOST | |Switch|
+-------+ +------+
| Register Msg |
| ----------------------->|
| |
| Notification Msg |
| <-----------------------|
| |
| |
Figure 4 : Host Device
4.3. Network Device
Switches manage the registration information of the hosts and storage
devices, and monitor the network status. Switches will synchronize
this information to the other switches in the network.
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+------+ +------+
|Switch| |Switch|
+------+ +------+
| Information Sync |
| ----------------------->|
| |
| |
| |
Figure 5 : Network Device
5. Procedures
5.1. IP Domain Management
On an FCoE network, users can control access between nodes through
zones, improving network security. This zone is used for inter-
domain isolation and intra-domain communication.
On the Ethernet-base NVMe network, we also need to implement FC zones
to isolate and control services between storage devices and hosts.
On the Ethernet-base NVMe network, IP addresses are used as the
unique identifiers of hosts and storage devices, and domains are used
as the attributes of IP addresses. Hosts and storage devices in the
same domain can access each other. Hosts and storage devices in
different domains are isolated. Each IP address needs to be assigned
to one or more domains. Also, there is a default domain. If no
isolation is required, the IP addresses of these hosts and storage
devices belong to the default domain. For each domain, we may also
call it zone.
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_,.---.,, ,,.--.,,
.'` `'., .'` `'.
,-` ,' `\
/ +--------+ ,' \ +--------+`.
.' |StorageA| / `, |StorageB| \
/ +---,----+ / \ +-_.-----+ \
/ `., / ,_-` \
' '/ _-\ ,
| |`', _-` | |
/ / +-`-`--+ \ \
| | |Switch| | |
| | +- .-,,+ | |
| | ,'` | '. | |
| |-` | `',| |
| .'| | |., |
, ,-` \ | / ', /
| +-----`-+ | +---\---+ | +-`'----+ |
, | HostA | \ | HostB | / | HostC | `
\ +-------+ \+-------+ ` +-------+ /
\ \ / /
`. \ ' /
\ `, ,' `
`. Zone1 `. Zone2 ,'
`'., _.-` '., _.'`
`'''--''` `''--''`
Figure 6 : Zone Management
As shown in the figure above, HostA and StorageA belong to Zone1,
HostC and StorageB belong to Zone2, and HostB belongs to Zone1 and
Zone2.
StorageA can be accessed only by HostA but not HostC. StorageB can
be accessed only by HostC, but not by HostA. Because HostB belongs
to both Zone1 and Zone2, HostB can access StorageA in Zone1 and
StorageB in Zone2.
5.2. Network Deployment
The NoF network uses the standard Ethernet technology, and the
typical deployment model is the CLOS architecture. Network
deployments typically use the current IP technologies. For example,
OSPF is usually deployed as an underlay protocol.
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5.3. Storage and Host Access
Hosts and storage devices are connected to the ethernet network. The
administrator assigns access IP addresses to the hosts and storage
devices. In most scenarios, these routes can be advertised through
the underlay protocol. In addition, after hosts and storage devices
go online, they need to register their information to the switches.
It is recommended that the registration message be completed using
LLDP.
The registration information includes the IP address type, whether to
subscribe to host or storage device information changes, device role,
service protocol type and version number, protocol service port
number, protocol identifier, etc.
The switch receives and saves the registration information of hosts
and storage devices. For a host/storage device that subscribes to
the hosts and storage device information changes, the switch also
needs to advertise the collected registration information to the
subscriber. The information to be advertised includes the device
status, device status change reason, and device attachment
information. When advertising the subscribed information, it must be
ensured that only the registration information of the domain to which
the node belongs is advertised. It is recommended to use a new
protocol to implement this notification message.
5.4. NoF Information Advertisement
Users assign domains for different hosts and storage devices. The
domain information must be obtained by all access switches on the
entire storage network. The domain information can be configured on
each access switch. It can also be configured on some switches and
then synchronize to all other access switches throughout the storage
network.
In addition, the local host and storage device registration
information stored on each access switch needs to be synchronized
across the entire switch network so that host/storage devices under
other access switches can obtain the information.
The synchronization information about the host and storage devices
belongs to the application layer's information. A new protocol
should be defined to implement the information synchronization.
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+-------+ +----+ +------+ +----+ +-------+
| HOST |-----------|TOR1|------|Spine1|------|TOR3|------|Storage|
+---/---+ +-/--+ +--/---+ +-/--+ +---/---+
|---------------->| | |<------------|
| Register Msg |----------->|<-----------| Register Msg|
| |<-----------|----------->| |
|<----------------| Info Sync | Info Sync | |
|Notification Msg | | | |
| | | | |
Figure 7 : Information Advertisement
6. Reliability Consider
6.1. Storage Failure
When a storage device is faulty, the access switch detects the fault
and spreads the fault on the network. After receiving the fault, the
host that subscribes to the storage device can switch to another
storage device. The switchover is performed by the host side. The
network side needs to quickly notify the host of the fault.
6.2. Host Failure
When a host is faulty, the access switch detects the fault and floods
the fault on the network. Hosts and storage devices determine
whether to subscribe to the fault status of a specified host based on
the implementation.
6.3. Access Link Failure
When an access link is faulty, the access switch detects the fault
and spreads the fault on the network. After receiving the fault, the
host that subscribes to the storage device can switch to another
storage device.
To accelerate fault detection, BFD or other fast detection
technologies can be used to accelerate it.
6.4. Network Link Failure
ECMP or redundant link protection is usually deployed to prevent this
failure.
When multiple links fail on the network side, the switch network may
be split. In the two split networks, each host receives the
corresponding notification and performs different serves on the
storage devices.
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6.5. Network Device Failure
The fault is equivalent to a network link fault or an access link
fault or both.
7. Security Considerations
TBD
8. IANA Considerations
This document makes no request of IANA.
9. Acknowledgements
NA
10. References
10.1. 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>.
10.2. References
[ODCC-2020-05016]
Open Data Center Committe, "NVMe over RoCEv2 Network
Control Optimization Technical Requirements and Test
Specifications", 2020.
Authors' Addresses
Haibo Wang
Huawei
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: rainsword.wang@huawei.com
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Lily Zhao
Huawei
No. 3 Shangdi Information Road
Beijing
100085
P.R. China
Email: Lily.zhao@huawei.com
Shuanglong Chen
Huawei
No. 156 Beiqing Road
Beijing
100095
P.R. China
Email: chenshuanglong@huawei.com
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