iSCSI vs. FC for meeting mission critical requirements.

Mission-critical data is just what its name says: critical to the core functioning of an enterprise. Mission-critical data must be available 24x7 and fully backed up for immediate recovery in the event of disaster. Enterprises are constantly seeking more reliable, more efficient, more convenient and more affordable ways of meeting these needs. iSCSI switches use technology that centrally consolidate, manage, backup and restore mission-critical data at a fraction of the cost--in capital and human resources--of existing FC SAN technologies.

Mission-Critical Requirements and iSCSI Solutions

Storage Area Networks (SANs) are used to manage mission-critical data and, as they have developed, storage and network administrators have identified three main requirements on a SAN to manage this critical data:

* High Availability: Storage systems and their mission-critical data must be available 24x7. There is no leeway for downtime. Every minute of downtime equals a loss of revenues and credibility for an enterprise.

* Remote Backup and Recovery: Data must be backed up off site to enable remote recovery in the event of disaster. Experts estimate that 30% of companies could not recover from a catastrophic loss of data and having backups on premises is of no use if the premises are destroyed.

* Manageability: A SAN management system must be able to be centrally managed and provide a consolidated storage solution accommodating different storage subsystems and infrastructures. In addition, the SAN management must not exert added strain on the network and storage administration staff.

Dynamic Expendability

Storage networks must be able to grow with an enterprise. Systems cannot be taken offline to accommodate this growth and no one wants to search for new storage management solutions every time there is a growth spurt.

One iSCSI vendor, SANRAD, has taken these requirements and provided comprehensive solutions in a single centrally managed platform using iSCSI technology.

High Availability

SANRAD's iSCSI V Switch hardware is fully redundant to weather power, processor and fan failures. The switch configuration database is written to both flash and compact flash memory. The software IP-based SAN configuration provides automatic switch failover and failback, as well as data mirroring. No single point of failure ensures high availability.

Remote Backup and Recovery

The iSCSI switch can create global IP-based storage networks to allow mission-critical data transfer to remote sites within the IP SAN.

Manageability

The iSCSI switch enables storage pooling across multiple platforms and infrastructures and eliminates the need for host agents. The V Switch functions at the network layer and is therefore independent of host OS and storage vendors. The switch provides storage virtualization and precise LUN carving of the pooled storage, supporting volume concatenation, mirroring and striping. The locally accessed GUI-based Vintage management server is used to centrally configure volumes, monitor status and manage the storage pool.

Dynamic Expendability

The iSCSI switch uses existing adapters, network and disk subsystems to form a sophisticated SAN solution ranging from 72GB to 16TB. New storage devices can be added dynamically and their volumes virtualized in real time without taking the system offline or impacting on functioning volume performance. Two V Switches from SANRAD can be combined in a SAN to from a cluster to provide inter-V Switch load balancing and failover.

Benefits of iSCSI SAN Over FC SAN

When creating a SAN, enterprises find that the traditional answer is FC SAN. However, the investment required to implement an FC SAN is often beyond the means of a young enterprise. As a result, growing enterprises may find themselves delaying the inevitable upgrade to a SAN and, therefore, gambling with their mission critical data store.

The FC investment comes from four fronts:

* Infrastructure: An FC network demands FC switches, hubs and bridges along with specific GBICs and cabling. In addition, each host requires dedicated FC HBAs.

* Storage Devices: The storage devices must be costly FC RAID arrays. If an enterprise wants to maintain its JBOD stores, it must purchase virtualization appliances to convert the JBODs for use in an FC SAN.

* Software: A variety of software tools is needed to manage all of this new equipment as well as the dedicated FC HBAs.

* Human Resources: A dedicated group of FC storage and networking IT administrators is needed to manage all of this.

For a growing enterprise, this represents a sizable investment in capital and human resources to acquire, implement and manage only one aspect of the enterprise's data flow.

An iSCSI switch such as SANRAD's V Switch provides a single integrated hardware/ software solution to SAN management:

* Infrastructure: The iSCSI switch uses an enterprise's existing IP infrastructure including existing Ethernet switches, cabling, GBICs and SFPs. A host's existing NIC is all that is needed to connect to the SAN.

* Storage Devices: The iSCSI switch supports existing legacy storage devices, both FC & SCSI, RAID & JBOD, so there is no need to purchase new storage devices. Due to the storage pooling capabilities of the SANRAD V-Switch, enterprises may have an increase in usable storage space.

* Software: The iSCSI switch has both a hardware and a software component. There is no need for additional software beyond the included Vintage storage management tool.

* Human Resources: Because the iSCSI switch operates over the enterprise's existing Internet network, minimal additional knowledge or training is needed to implement or manage the SAN. The existing network or storage administrator is readily qualified to manage an iSCSI SAN.

Business Case: iSCSl V Switch vs. FC

Typical SAN topographies can be divided into 5 groups according to the number of servers accessing the SAN and the net storage capacity of the SAN:

* Small: 8 servers accessing a net capacity of 500GB.

* Small-Medium: 12 servers accessing a net capacity of 1TB.

* Medium: 16 servers accessing a net capacity of 1.5TB.

* Medium-High: 24 servers accessing a net capacity of 2TB.

* High: 32 servers accessing a net capacity of 3TB.

To best understand the budgetary impact of implementing an FC SAN compared to an iSCSI SAN, consider the costs of each for a medium enterprise with sixteen hosts accessing a storage pool of 1.5TB.

In an FC SAN, this would require two FC switches. Upstream of the FC switches there are five server clusters, including Exchange, SQL and file servers, plus six individual servers. Each server requires FC software and each server has two HBAs, each connected to a different switch for a total of thirty-two HBAs. Downstream of the FC switches is a RAID system with RAID-5 and hot spare capabilities and a net capacity of 1.5TB. The cost of such a network is shown in Table 1.

An iSCSI SAN provides all of the key SAN requirements needed to manage, backup and restore mission critical data with added benefits over FC SAN. An iSCSI switch represents a single integrated hardware/software solution to SAN management, including storage pooling, virtualization, mirroring, striping and remote backup. A SANRAD IP-based iSCSI SAN permits remote storage access and provides greater flexibility in the location of network and storage components within an enterprise and it does so at a fraction of the cost of an FC SAN.

Table 1--Small Enterprise PC SAN Configuration for Mission Critical
Data

Hardware or Software                      FC Cost

32 x FC HBAs                             $  48,000
16 x Host-base FC SW (e.g. Power Path)   $  24,000
2 x 32-port FC Switch                    $  84,000
1.5TB Dual RAID system (RAID-5)          $  51,000

Total                                    $ 207,000

Table 2--Small Enterprise iSCSI SAN configuration for Mission Critical
Data

Hardware or Software                      iSCSI Cost

2 x 24-port Gbit Switch                   $  4,800
2 x iSCSI V Switch 2000                   $ 25,000
4 x 16-slot JBODs with 40x73GB (Mirror)   $ 32,000

Total                                     $ 61,800

www.sanrad.com

Shaul (Uli) Gal-Oz is chief executive officer of SANRAD