Maximizing FC SAN investments with iSCSI.

Businesses have made significant investments in their Fibre Channel storage area networks. The challenge is to leverage the FC SAN so that these investments in capital equipment, staff and infrastructure deliver ever-increasing value to the business. The majority of the FC SAN investments are not raw disk capacity, but infrastructure costs such as: disaster recovery mechanisms, high availability systems, backup, monitoring, security and resource allocation tools. Equipment investments include: FC switches, routers, storage enclosures, host HBAs and backup devices. Soft dollars include management, staff, software agents, upgrades, maintenance and facility.

Increased FC SAN ROI and value comes by increasing productivity, which means adding more users, encompassing a greater number of application servers and expanding the total amount of hosted data. Many businesses have been reluctant to put more servers and clients on the SAN. High per-server attachment costs and management complexity are major factors limiting the expansion of FC SANs. This has created a dilemma for many IT managers who want to fully utilize their FC SANs but find it difficult to justify the addition of more servers or clients.

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Strategic Option: Expanding the SAN with Ethernet

A new standard for expanding SANs was required that would allow businesses to realize the full benefits of their FC SAN investments by greatly reducing the costs associated with connecting servers to the FC SAN. The IETF/IEEE committee and industry leaders worked together to create the new iSCSI storage protocol. iSCSI solved many of the problems causing the slow expansion of FC SANs. This new storage protocol resides on top of TCP/IP over Ethernet. Unlike Fibre Channel, iSCSI uses Ethernet and does not require special equipment or cabling. It can use common Ethernet NICs (network interface cards), switches, hubs and cabling.

The Benefits of iSCSI are Clear for Expanding FC SANs:

* Based on IETF standards to insure interoperability

* iSCSI SAN connectivity costs are 1/2 to 1/5 that of FC

* Uses existing Ethernet cabling and existing network elements

* Uses common TCP/IP for global connectivity

* Leverages the existing expertise of IT professionals

* Is being quickly adopted by system, storage, and network vendors

* Provides the same reliability as FC

Leverages IP Security (e.g. SRP, CHAP, and IPSEC) Table 2 shows relative costs for connecting application servers using FC vs. connecting the same servers or clients to an iSCSI / Ethernet Storage Network.

iSCSI to FC Gateways

Using an iSCSI gateway to the FC SAN can increase the number of application servers and clients storing their data within the FC SAN infrastructure. A gateway resides at the edge of the FC SAN, between the FC SAN and Ethernet network. Hosts traffic data using iSCSI between themselves and the gateway over a common Ethernet network. The gateway converts the traffic to FC and routes it to the designated storage LUNs within the FC SAN. Gateways are equipped with 2 to 4 FC Ports for connecting to the SAN and an equal number of Gb Ethernet ports for connecting to the Ethernet network. New hosts connected to the same Ethernet network will be able to access the FC SAN through the gateway.

The SAN infrastructure does not need to change when attaching the gateway. The gateway is attached via its FC ports that resemble host HBAs. The FC SAN administrator simply needs to provide access to storage LUNs for the gateway, just as it would provide storage resources to a basic server. The gateway will discover and log on to the storage resources and read and write to them in the same manner as an FC server. Figure 1 shows a typical high availability configuration with clustered gateways being used to connect iSCSI enabled servers to the FC SAN.

Volume Management Within the Gateway

One of the major issues in extending a SAN using a gateway is the task of managing the storage resources for a few to hundreds of new hosts and clients. The number of hosts and clients connected over iSCSI can become a fairly high number and be distributed over a large geographic area or even into another country. Traditional methods for volume management are far too expensive, complex and maintenance intensive to support this type of infrastructure.

iSCSI connected hosts and clients can receive their storage resources and volumes from the gateway. A gateway with sophisticated volume management, storage virtualization and access control provides the best platform for providing storage services to iSCSI-connected hosts. This allows hosts and clients to be connected at will. They require no agents and no additional software. All that is needed is a generic iSCSI driver. Any authenticated server, desktop or laptop can now use storage resources from the FC SAN. This makes attaching, replacing and upgrading individual servers a simple task and provides the perfect platform for clustering, databases, data replication, backup and other business applications.

Volume management is done using storage virtualization. As stated earlier, the gateway receives control over FC resources or LUNs within the SAN, just like a server on the SAN. But these LUNs are not necessarily exposed as is to hosts connected with iSCSI. Instead, the storage resources are placed into a large storage pool managed by the gateway. From this central pool, new simple and complex volumes are created. It is these new "virtual" simple and complex volumes that are used by the iSCSI connected hosts and clients. Complex virtual volumes can be created to support mirroring and/or striping across any allocated resource within the FC SAN.

Table 3 compares the overall costs of connecting FC servers and the license fees associated with host agents to enable volume management vs. the cost of delivering volume management from a central gateway that in host independent and does not require host agents.

Conclusion

Businesses have made significant investments in their FC SANs. The challenge is to leverage the FC SAN so that these investments in capital equipment, staff and infrastructure deliver ever-increasing value to the business. Increased FC SAN ROI and value can be realized by adding more users, encompassing a greater number of application servers and expanding the total amount of hosted data.

Additional hosts can be very cost effectively connected to the FC SAN using iSCSI and an iSCSI to FC gateway. The number of hosts and clients connected over iSCSI can become a fairly high number and hosts and clients can be distributed over a large geographic area or even into another country. The cost of connecting a host using iSCSI is far less than connecting a host using traditional FC.

One of the major issues in extending a SAN using a gateway is the task of managing the storage resources for a few to hundreds of new hosts and clients. Traditional methods for volume management are far too expensive, complex and maintenance-intensive to support this type of infrastructure. A gateway with sophisticated volume management, storage virtualization and access control provides the best platform for providing storage services to iSCSI-connected hosts. This makes attaching, replacing and upgrading individual servers a simple and low-cost task and provides the perfect platform for clustering, databases, data replication, backup and other diverse business applications.

SANRAD's iSCSI V Switch is a FC SAN gateway that gives the IT professional all the tools needed to extent a FC SAN with iSCSI.

Storage Applications and Requirements delivered by iSCSI V Switch Products:

* FC SAN expansion to iSCSI enabled hosts

* Agent and host free custom storage virtualization

* Network-centric data mirroring and data migration

* Centralized virtualization across large FC SAN storage pools

* High-availability, multi-pathing and failover

* Security and Access Control

* Departmental self-management of SAN resources.

Table 1- Costs associated with a small mid-range SAN

10TB FC SAN                                            Cost

Racks/Enclosures / RAID Controllers                $200,000
Switches, Routers and Cabling                       $60,000
Tape Backup Device--Media                           $25,000
Management and Staff                               $150,000
Facility and Maintenance                            $25,000
Software Tools and Upgrades                        $100,000
Infrastructure Total (without raw disk)            $560,000

Raw disk capacity (1TB for $10k)                   $100,000

Table 2

Cost of Connecting a Server/Client to the SAN

                                           Fibre
Description                                Channel   iSCSI

Single Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 1HBA)          $750      $0
Standard Switch Port                          $750     $50
Total                                       $1,500     $50

Single Path--High Performance Application
Line Speed Connection (HBA)                 $1,000    $500
High Performance Switch Port                $1,500    $250
Total                                       $2,500    $760

Multi Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 2HBAs)       $1,500      $0
Standard Switch Port (2X)                   $1,500    $100
Total                                       $3,000    $100

Multi Path High Performance Application
Line Speed Connection (2X HBA)              $2,000  $1,000
High Performance Switch Port (2X)           $3,000    $500
Total                                       $5,000  $1,500

Cost of Connecting a                        Cost of Adding Multiple
Server/Client to the SAN                    Servers and Clients

Description                                 No. of Fibre-channer Servers

Single Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 1HBA)
Standard Switch Port                              5       10        20
Total                                        $7,500  $15,000   $30,000

Single Path--High Performance Application
Line Speed Connection (HBA)
High Performance Switch Port                      5       10        20
Total                                       $12,500  $25,000   $50,000

Multi Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 2HBAs)
Standard Switch Port (2X)                         5       10        20
Total                                       $15,000  $30,000   $60,000

Multi Path High Performance Application
Line Speed Connection (2X HBA)
High Performance Switch Port (2X)                 5       10        20
Total                                       $25,000  $50,000  $100,000

Cost of Connecting a                        Cost of Adding Multiple
Server/Client to the SAN                    Servers and Clients

                                          No. of iSCSI/Ethernet
Description                                         Servers

Single Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 1HBA)
Standard Switch Port                             5        10         20
Total                                         $250      $500     $1,000

Single Path--High Performance Application
Line Speed Connection (HBA)
High Performance Switch Port                     5        10         20
Total                                        3,750    $7,500    $15,000

Multi Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 2HBAs)
Standard Switch Port (2X)                        5        10         20
Total                                         $500    $1,000     $2,000

Multi Path High Performance Application
Line Speed Connection (2X HBA)
High Performance Switch Port (2X)                5        10         20
Total                                       $7,500   $15,000    $30,000

Table 3

Cost of Connecting a Server/Client to the SAN

                                           Fibre
Description                                Channel   iSCSI

Single Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 1HBA)        $750      $0
Standard Switch Port                        $750     $50
Volume Management
Total                                     $1,500     $50

Multi Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 2HBAs)     $1,500      $0
Standard Switch Port (2X)                 $1,500    $100
Volume Management
Total                                     $3,000    $100

                                          Cost of Adding Multiple
Cost of Connecting a                      Servers and Clients with
Server/Client to the SAN                  Volume Management

                                          No. of Fibre-Channel Servers--
Description                                 Charged per User/CPU
                                              Assumes $2000 per

Single Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 1HBA)
Standard Switch Port                            5         10        20
Volume Management                         $10,000    $20,000   $40,000
Total                                     $17,500    $35,000   $70,000

Multi Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 2HBAs)
Standard Switch Port (2X)                       5         10        20
Volume Management                         $10,000    $20,000   $40,000
Total                                     $25,000    $50,000  $100,000

Cost of Connecting a                      Cost of Adding Multiple
Server/Client to the SAN                  Servers and Clients with
                                          Volume Management

                                           No. of iSCSI/EthernetServers
                                           Flat Network Centric Charge
Description                                  Assumes Flat Fees

Single Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 1HBA)
Standard Switch Port                            5         10        20
Volume Management                          $5,000    $10,000   $10,000
Total                                      $5,250    $10,500   $11,000

Multi Path--Standard Speed Application
Driver Only--<15 MBs-(FC Needs 2HBAs)
Standard Switch Port (2X)                       5         10        20
Volume Management                         $10,000    $20,000   $20,000
Total                                     $10,500    $21,000   $22,000

RELATED ARTICLE: You? A WestWorld Editor?

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Zophar Sante is VP market development at SANRAD (San Jose, CA)

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