Internet Protocol Storage Area Networks (IP SAN) - pudn.comread.pudn.com/downloads168/ebook/772307/STF3-4IPSAN.pdf · IP Storage Area Networks ... TCP/IP based tunneling/encapsulating
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
IntroductionTraditional SAN technology is built around Fibre Channel.
IP technology is emerging as an alternative or supplemental transport for storage traffic.
= IP= FC
Switch
Servers Servers
Servers Servers
Switch
Storage Storage
Traditionally, IP network traffic has been at the file system level. Now, emerging technologies provide for the transfer of block-level data over an existing IP network infrastructure.
IP is being positioned as a storage transport because: IP management is easier. (Note: Many administrators are already familiar with it.)Existing network infrastructure can be leveraged, reducing the cost when compared with an investment in new SAN hardware and software.IP supports multi-vendor interoperability.Many long-distance disaster recovery solutions already leverage IP-based networks.Many robust and mature security options are available for IP networks.
IP encapsulation done on host / HBA(host bus adapter)Hardware-based gateway to Fibre Channel storage
FCIP– Fibre Channel-to-IP bridge /
tunnel (pointto point)
Fibre Channel end points
iFCP– IP as the inter-switch fabric
Fibre Channel end points
IPIPIP
IPIP FCFC
“Block storage over IP” represents several different approaches to moving block-level (channel) I/O over IP networks. The three protocols that are gaining most visibility today are iSCSI, FCIP, and iFCP. Each of these protocols leverages IP to extend and add value to the connectivity between hosts and external storage. Following are brief descriptions of each of these protocols.
iSCSI – Host-based encapsulation of SCSI I/O over IP using an Ethernet NIC card. IP traffic routed over network to either a box that extracts the SCSI I/O from the IP packets and sends these on to FC-based external storage, or an iSCSI storage array that handles the conversion and I/O “natively” inside the box.FCIP – Tunneling involving a pair of bridges with Fibre Channel that uses IP as the transport protocol. It is typically used to extend Fibre Channel networks over greater distances and/or over existing IP-based infrastructures.iFCP – Fibre Channel switches that use IP as the inter-switch “fabric” protocol. Again, utilizes existing IP infrastructure (cabling, switches, etc.) to support server-to-storage communications.
Today, there are three approaches to block storage over IP. They are ordered from top to bottom by commonality with Fibre Channel:
FCIP – TCP/IP based tunneling/encapsulating protocol for connecting/extending Fibre Channel SANs. The entire FC frame is sent over IP links.iFCP – Gateway-to-gateway protocol for FCP over IP. Mapping natively in IP acrossFibre Channel and IP. An IP-based tunneling protocol for interconnecting Fibre Channel devices together in place of Fibre Channel switches. When iFCP creates the IP packets, it inserts information that is readable by network devices and routable within the IP network. iFCP wraps Fibre Channel data in IP packets but maps IP addresses to individual Fibre Channel ports.iSCSI – Native TCP/IP protocol. An IP-based protocol for establishing and managing Connections between IP-based storage devices, hosts, and clients. No Fibre Channel content, but bridging between iSCSI and FC is possible.
NativeAll Ethernet (No Fibre Channel)iSCSI ProtocolEthernet Switches & Routers
BridgingServers - Ethernet AttachedStorage - FC Attached (SAN or DAS)iSCSI Protocol
ExtensionServers & Storage - SAN AttachedFCIP or iFCP ProtocolSRDF
= IP= FC
= IP= FC= IP= FC
Topologies for IP SAN include:Native – iSCSI allows for all communications using Ethernet. Initiators may be directly attached to iSCSI Targets or may be connected using standard Ethernet routers and switches. Bridging – Architectures allow for the Initiators to exist in an Ethernet environment while the storage remains in a Fibre Channel SAN.Extension – Architectures are most often used to provide connectivity across large distances. Either FCIP or iFCP bring the long distance benefits of IP to Fibre Channel.
Easy to leverage IP equipment and expertise to help manage data in conjunction with Fibre Channel SANs.
Fibre Channel SAN challenges include:High acquisition costSeparate infrastructureSeparate management model
IP SAN enablers include: Availability of Gigabit Ethernet and optical networking productsAvailability of managed Ethernet/IP-based Metro and WAN connectivity servicesIncreased availability of dark fiber and xWDM solutions in the metro
Easy to leverage IP equipment and expertise to help manage data in conjunction with FibreChannel SANs.
IP provides greatest flexibility at lowest cost for latency-tolerant applicationsSuitable for backup across campus network, MAN, or WAN
Most organizations already have IP networks and familiarity with traditional network management.
Leverages existing Fibre Channel applications.
Most organizations already have IP networks and familiarity with traditional network management. Thus, it is easy to leverage IP equipment and expertise to help manage data in conjunction with Fibre Channel SANs
Leverages existing Fibre Channel applications. This leveraging:Preserves existing Fibre Channel infrastructure and investments.Fully supports Fibre Channel fabric services across the LAN/WAN.Makes the IP Network seem transparent to the FC fabric.
IP Extends Fibre Channel applications over regional/global distances.
At higher link speeds, IP can handle synchronous applications.
Standard Fibre Channel Distances include:1 Gbps multimode fibre - maximum distance = 500 m1 or 2 Gbps single mode fibre - maximum distance = 10 KmWith DWDM, up to 200 Km
IP Extends Fibre Channel applications over regional/global distancesLAN, MAN, or WAN distancesA typical application includes remote backup and restore.
At higher link speeds, IP can handle synchronous applications such as:Disk mirroringShared storageData sharing
Describe the IP convergence in the SAN and its implications.
List the three common IP SAN approaches.
List the three deployment models (topologies) for IP SAN.
A SAN is a dedicated storage network that solves many of the complex business data storage needs. IP SAN is a cost effective solution for extending an FC SAN. The three most common approaches to creating an IP SAN are:
Upon completion of this lesson, you will be able to:
Describe and discuss the basic architecture of – FCIP– iFCP– iSCSI
This lesson describes the three common protocols for IP SAN. It introduces each of the protocols and describes the architectures and technologies for each.
Fibre Channel over IP - FCIPEncapsulates FC frames in IP packets.
Creates virtual FC links that connect devices and fabric elements.
Includes security, data integrity, congestion and performance specifications.
IP Datagram
IPHeader
TCPHeader
FCIPHeader IP PayloadIP Payload
Fibre Channel Frame
SO
F FCHeader C
RC
EO
F
SCSI DataSCSI Data
FCIP EncapsulationFCIP Encapsulation
Fibre Channel over IP (FCIP) moves encapsulated Fibre Channel data through a "dumb" tunnel, essentially creating an extended routing system of Fibre Channel switches.
Gateway-to-gateway protocol– IP switches & routers replace FC switches– Transparent to FC drivers
FC transport uses TCP connections– Point-to-multipoint networking possible
IPHeader
TCPHeader
iFCPHeader IP PayloadIP Payload
Fibre Channel Frame
SO
F FCHeader C
RC
EO
F
SCSI DataSCSI Data
iFCP Address Translation &Encapsulation
iFCP Address Translation &Encapsulation
The iFCP specification defines iFCP as a gateway-to-gateway protocol for the implementation of a Fibre Channel fabric in which TCP/IP switching and routing elements replace Fibre Channel components.
The protocol enables the attachment of existing FC storage products to an IP network by supporting the fabric services required by such devices.
Flexible and can function as a(n):IP Tunnel for FC-to-FC FCP data transport.Bridge for FC-to-IP FCP data transport.Replacement for FC for IP-to-IP FCP data transport.
iFCP has less potential bottlenecking vs. FCIP since it has a TCP session for every virtual port-to-port connection.
iFCP maps Fibre Channel transport services to an IP fabric. In this implementation, gateways are used to connect existing Fibre Channel devices to an IP network and, as such, will include physical interfaces for both Fibre Channel and IP.
iFCP is a TCP/IP protocol that transports encapsulated frame images between gateways. iFCP session end points are Fibre Channel N_Ports.
IP services are in effect for all individual devices and standard IP routing, naming, security, quality of service, and class of service can be used. Device discovery can be automated by standard methods such as SLP (Service Location Protocol), iSNS (Internet Simple Name Service), or can be manually configured.
Local Mode:Means the Gateway region creates “phantom” FC addresses for foreign nodes.Is more flexible since FC switch domain IDs can be duplicated in each region.
Address Transparent Mode means all gateways share addressing.
Routing between gateway regions is IP-only and FSPF and DFS stay in the region.
In the example Zoning and Name Server information sharing allows SAN A devices to be visible to SAN B devices and vice versa. Zones are exported from one gateway device to the other.
A method to transfer blocks of data using the TCP/IP network.
Serialized service delivery subsystem.
SCSI protocol over IP.
A method to transfer blocks of data using the TCP/IP network.
Serialized service delivery subsystem.
SCSI protocol over IP.TCP is a reliable transport that retransmits dropped packets.IP is an unreliable transport mechanism (packet dropping allowed).Ethernet (10/100/1G/10G) is a popular Physical Transport layer.
The SCSI commands are intercepted by an iSCSI initiator and passed to the TCP stack. Once passed to the TCP stack, the commands are transmitted across the network to a target.
The SCSI commands are exposed once the packet has passed back up the target stack. When the SCSI commands are exposed, the action requested is passed onto the SCSI device for which they were destined. The device performs the requested action.
Due to the shared nature of the connectivity to the storage target, an administrator has two options for connectivity management:
1. Each initiator can be individually configured with a list of its authorized targets and each target can be configured with is list of initiators and access controls
2. An iSNS server can be configured with a list of initiators and targets, which can be done dynamically. Additional information can also be stored such as:
• Discovery Domains which organize the resources into manageable groups• Change State Services which provide notification of storage node change of state
e.g. going off line, domain membership changes, IP link status, etc.• Fibre Channel and iSCSI device mappings.
Within iSCSI, a Node is defined as a single Initiator or Target. These definitions map to the traditional SCSI Target/ Initiator model. iSCSI Names are assigned to all Nodes and are independent of their associated address.
There are two major network components associated with iSCSI:The Network Entity, the specific device or gateway accessible to the IP network. The network component is the Network Portal.
TCP Session Basis - Manual definition of virtual ISL path
Dynamic by node-to-node login
Dynamic by node-to-node login
Intermediate
-
Low
Conversion Overhead
- Low Medium High
Medium
YES
YES
Medium
Simple Name Service
Manual/iSNS/SLP Manual/iSNS/SLP
IP Routable Per Virtual ISL Per Connection Per Connection
Relative Distance Long Unlimited Unlimited
FC Content Full Frames FCP None
Transmitted Overhead
High Medium Medium
Resiliency Low High High
Fabric Contiguity YES NO NO
Port Aggregation YES YES YES
Scalability Low High High
This table is provided as a general, high-level reference to these protocols. It is subject to situation-specific interpretation and is only presented as a learning aid. The fact that many items are not applicable for native FC demonstrates some of the extensibility that IP protocols can add to the SAN.
A SAN is a dedicated storage network that solves many of the complex business data storage needs. IP SAN is a cost effective solution for extending an FC SAN. The three most common approaches to creating an IP SAN are:
Upon completion of this lesson, you will be able to:
Describe common applications of IP SAN technology such as:– Remote Backup and Restore– Remote Data Replication– Storage Consolidation
So far, we have looked at the benefits of an IP SAN and the connectivity methods for implementing and IP SAN. This lesson provides an overview of the common applications for IP SAN technology.
The objectives for this lesson are shown here. Please take a moment to read them.
Customer data can be backed up at an offsite remote data center. This data center may be in the same metropolitan area, or it may be in a separate geographical region.
In case of data loss, backup is accessible directly over the MAN/LAN. A solution such as this could be implemented with either FCIP or iFCP. The IP network cloud could be extended to engulf the FC SANs in the picture using iFCP or iSCSI natively and no FC components would be required.
Data may be replicated from one site to another across the MAN/LAN. In this application, customer data is kept continuously synchronized across the network. Each site stores live production data. For example, this application could be used to deliver rich media content to distribution centers near users.
Once again, iFCP or FCIP could be used to achieve this as shown. iFCP or iSCSI could perform a similar function if the IP network cloud was extended to encompass the FC SANs shown in the diagram.
Both iFCP and iSCSI can be used to create FC-free SANs. These SANs could be significantly more than what is shown here. As long as response times are within acceptable limits for the applications in question, there is essentially no distance limit for these SANs built on IP technology. Any of the IP switches represented above could be replaced with an iSCSI or iFCP gateway device to allow native FC SAN islands to communicate.
The IP convergence in the SAN and its implications
The basic architecture of FCIP
The basic architecture of iFCP
The basic architecture of iSCSI
Application of IP SAN technology
In previous modules, we looked at DAS, NAS and FC SAN storage connectivity. This module introduced the Internet Protocol Storage Area Network (IP SAN). We looked at the components and connectivity methods for an IP SAN as well as management topics and applications of IP SAN technology.