Introduction to SANs: Technology, Benefits, and Applications

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For most business users the demand for storage is being stimulated by companies and users coming to the realization that the one thing on their computers they keep, upgrade after upgrade, generation after generation, are the stored data files.

The rapidly growing demand for storage can affect any enterprise, be it a large company or a small office. Large companies can find great numbers of distinct storage devices expensive and complex to manage, especially when the storage devices are heterogeneous, that is, when they have a wide variety of different storage drives and device types to manage. Small offices can also feel the pinch of rapid storage growth when their storage consumption doubles every year, and they find they lack the information management personnel to modify their network infrastructure and applications to accommodate their expanding number of storage devices.

With the advent of SANs, IT managers finally have a way to aggregate storage resources to a central repository that not only easier to manage but more scalable and more reliable compared to current distributed storage infrastructures.

What is a SAN

?”>

A Storage Area Network is a special purpose high-speed network that provides direct connections between storage devices (which henceforth will be referred to as “targets”) and servers (often referred to as “initiators” in the storage world). In todays current marketplace, SANs are almost synonymous with Fibre Channel, a computer, storage, and network device communications protocol designed for high performance information transfer that is capable of high bandwidth (100MB/s and beyond), flexible topologies, and connectivity over several kilometers.

First and foremost, it is extremely important to remember that a SAN is indeed a network and that, over the course of its evolution, the SANs seen in IT organizations will contain a mix of networking connectivity options, including Fibre Channel, the emerging iSCSI, and the Fibre Channel over IP standards like iFCP. Since the vast majority of software and hardware for SANs are Fibre Channel based, we will focus on the benefits and limitations of current fibre channel based SANs in this article.

The goal of a SAN is to integrate different types of storage subsystems such as high-throughput RAID, high-transaction rate RAID, near-line long-term archival storage, and short-term backup storage into a single system. SAN resources are made available to users through partitioning or through a single shared file system. A SAN can also enable direct storage-to-storage interconnectivity, and allows administrators to exploit new breeds of clustering technology and intelligent device sharing to provide disk storage and tape backup services to one or more servers.

The advantages of a SAN include: improved performance via the use of storage networking hardware thats faster than traditional server-attached storage, and improved accessibility and scalability of storage resources by permitting users to access those resources through multiple servers. They also make it easy to add storage and servers without downing the network, and more importantly, they provide redundancy.

Who Can Use a

SAN?”>

Given the current state of the fibre channel market, the deployment of SANs is generally only recommended for large enterprise-class companies, though mid-size and smaller companies with proper support infrastructure can also derive benefits for various applications. Interoperability is still a problem facing early technology adopters and it will continue to be a problem as the standard continues to evolve to 2Gbps speeds and beyond.

SANs are generally beyond the ability of most users to build. One of the unfortunate truths about SANs is that their networking technology, particularly fibre channel, is still a relatively new technology compared to more established network protocols and interface standards like Ethernet or SCSI. This shortcoming leads to incompatibilities between hardware made by different manufacturers. Custom SAN system manufacturers like EMC, IBM, and Compaq do extensive testing and compile lists of compatible hardware. However, companies that build fully integrated SANs are fully plug-and-play from the users perspective.

Small scale SANs can be deployed in workgroups that are trying to leverage fibre channels device sharing capabilities (ex. Using fibre channel to set up a shared LAN-free backup infrastructure–more on backup solutions later), but this scenario is highly discouraged for companies that dont have fibre channel expertise in house.

For the most part, for shared storage needs, we highly recommend that small companies use NAS (Network Attached Storage) appliances to centralize the storage needs of their workgroups. NAS can be installed into an existing Ethernet network in a matter of minutes, and although its performance will be somewhat less than that of a SAN, the performance degradation wont be noticeable to most clients. For a detailed comparison of these two technologies, please refer to the SAN vs NAS section of this article

How are SANs Better

Than Current Storage Options?”>

In order to truly appreciate the benefits of a SAN we need to carefully examine the current state of distributed systems and their storage devices.

In traditional server-attached storage, all access to that servers storage resources are made through that single computer. As a result, the server itself can become a bottleneck if it needs to run too many applications or support too many users at once. Plus, users need a one-to-one relationship with a computer to use its resources. If only one computer on a network is running a particular application such as an e-mail system or a database, users have to connect with that machine.

Furthermore, current server-attached storage lacks the flexibility to move storage resources. For example if a large UNIX server has a 100 GB of spare storage space, an IT manager cannot reallocate this resource to a storage-starved NT or Novell server. In a SAN environment, IT managers (using storage management tools) have the ability to resize the partitions on their centralized storage repositories and reallocate unused storage space to needy servers.

Host redundancy is another key feature lacking in direct-attached storage. When a host goes down in a distributed systems environment, the data held within that host is, for the most part, unreachable (unless the IT manager has a fault-tolerant cluster set up with disk mirroring). Since storage lives independently from the server in a SAN, if there is a server outage, an IT manager can easily shift the control of a storage volume to another server connected to the SAN.

SANs make it easy to add storage without the necessity of taking down a server. Since a SAN is a network, it is independent of any single device connected to it. To add a device, all thats necessary is to give the device a LUN (logical unit number) and connect it to the SAN. Once storage is added to a SAN, an IT manager can use this newly added storage to increase the size of a given storage volume. This makes the newly added storage available to all users and applications without having to reprogram every workstation or application. This is a key feature that makes SANs useful to large enterprises that are experiencing rapid growth.

Without a SAN, adding storage to a server requires taking that server down and interrupting operations, to back up data to tape. After data has been backed up, an administrator would have to blow away their current RAID setup, add the new disks to the enclosure, and restore their data back to the rebuilt storage unit. While this operation was acceptable for many businesses in the past, now that we are in the age of 24/7 E-Commerce, unnecessary downtime has become intolerable.

Partitioning is a method by which pooled storage is subdivided into smaller, more manageable volumes that can be allocated to specific applications, servers, clusters, etc. For example, a RAID system first pools multiple physical hard drives into a single large virtual volume. This large virtual volume can then be partitioned into smaller volumes. Each of the partitioned volumes on a RAID subsystem can be the same size as a single hard disk, but the volumes benefit from the redundancies and performance advantages inherent in RAID technology. Partitioning lets operating system file systems use disk space more efficiently. It gives system administrators flexibility when planning security and assigning users their storage access.

SANs can be partitioned just like a RAID system, only the partitioning takes place over the entire storage network rather than individual storage subsystems. So, if a SAN is composed of multiple RAID systems of various speeds, plus tape and optical archives, each partition of the SAN may include portions of these different storage resources.

Each partition is controlled by its own server, server cluster, or shared file system. System administrators have the freedom of assigning storage resources to different partitions in any combination. Each department in an organization might be allocated its own partition, and can determine its own file migration, redundancy, and backup requirements.

What Makes UP a

SAN”>

SANs link targets (storage devices) to initiators (servers or clients that initiate data traffic). Aside from the storage devices themselves, the most important devices that live on SANs are the networking infrastructure components; the hubs, switches, bridges, and routers that connect the storage devices and servers together on the SAN. Network infrastructure components are usually purchased through a SAN vendor and/or integrator as part of a complete SAN solution, and not as individual components directly by the end user.

Switches and Hubs
Switches allow the devices connected to them to communicate over a deterministic medium. Fibre Channel switches allow devices to communicate at the maximum possible speed since traffic is directed towards the proper target by the switch hardware. This is in contrast to a hub, where all the devices are connected to a shared bus, and the medium is contention based.

In a hub environment, a device broadcasts its data to all the ports on the hub simultaneously, and as a result only one device can use the hub at a time. The bandwidth on a hub is the roughly the same as that of a single switch connection. On a hub only one full bandwidth connection is shared among all the devices, while on a switch, every device gets the full bandwidth at the same time. Hubs are gradually being phased out in favor of switches, but IT managers should expect to still seem them around since the earliest Fibre Channel SANs from about 3 years ago were built on Fibre Channel hubs.

Brocade Communications Systems is the leading vendor in the Fibre Channel switch space, but comparable switches can be purchased from Vixel Corporation and Gadzoox Networks, Inc.

Interoperability between switches is still questionable, but with the emergence of the E port spec (which will allow fibre channel systems from different vendors to uplink to each other), IT managers will eventually be able to mix and match switches.

Host Bus Adapters (HBAs)
Fibre Channel Host Bus Adapters are installed into servers and they act as the gateway to SANs. On a physical level, fibre channel HBAs look quite similar to gigabit Ethernet HBAs. Fibre Channel HBAs usually slide easily into the 64-bit PCI slots of a server/workstation motherboard, and they can be installed in a matter of minutes.

From a software point of view, the device driver of a Fibre Channel HBA starts the storage virtualization process by fooling the servers operating system into thinking that it is a SCSI adapter. At first it may seem strange to make a networking component like an HBA (which connects to switches and hubs via fiber-optic cabling) look like a storage controller, but this virtualization is acceptable and works fine with the OS.

When a server boots up and the Fibre Channel HBA becomes initialized, the HBA sends out a broadcast message on the Fibre Channel network. When the available LUNs report back to the Fibre Channel HBA, the HBA reports the presence of these LUNs to the operating system as storage devices that it is managing. Once LUNs are recognized by the operating system, they can be managed by the operating systems disk and volume management systems, and can be carved into partitions, and eventually formatted in the file system of that operating system.

Storage virtualization is a tricky concept, which to this day is still evolving in the SAN industry. In future articles we will cover the different methods by which storage virtualization is achieved. For the purpose of this article, storage virtualization is the process by which a server operating system is fooled into thinking that storage resources on a SAN (which can physically be several kilometers away from the server) are actually locally attached to the server through the Fibre Channel HBA (which is masquerading as a SCSI adapter).

Fibre Channel HBAs are fairly pricey, with new state of the art 2Gbps fibre channel cards running over $2000 and lower end 1Gbps cards usually selling for over $1000 a card. For this reason, we recommend that workgroups that dont really need Fibre Channel for their day-to-day needs should definitely avoid rolling out this technology to low and midrange machines.

Emulex Corp. and Qlogic Corp. are major manufacturer of Fibre Channel HBAs. Hewlett Packard and Adaptec also produce Fibre Channel HBAs.

Fibre Channel/SCSI Routers
As the name implies Fibre Channel/SCSI routers allow the movement of data from the SCSI world to the world of Fibre Channel SANs. Fibre Channel/SCSI routers have ports for both SCSI devices and Fibre Channel, and they allow SCSI devices to present themselves to the SAN.

Early SAN implementations (back in the days when Fibre Channel-based hard drives were hard to acquire and costly) were built out of SCSI hard drives with Fibre Channel/SCSI routers built into the array enclosure. Today, most SAN hard disk storage offerings have full Fibre Channel designs for performance and implementation simplification purposes, but Fibre Channel/SCSI based routers are still prevalent, since the near-line and offline storage vendors have yet to catch up to their hard disk counterparts.

Currently the vast majority of tape drives and libraries are SCSI-based, a market fact that necessitates the use of Fibre Channel/SCSI routers in networks. For the most part, the majority of Fibre Channel-enabled Tape Autoloaders and Libraries entering the market from companies like ADIC are really nothing more than SCSI-based storage units with integrated Fibre Channel/SCSI routers that have gigabit connectors allowing them to hook directly into SANs.

Considering the vast market acceptance of SCSI-based autoloaders, libraries (tape and optical), and standalone tape drives, we expect SCSI storage products to co-exist with SANs for many years, a reality that will allow Fibre Channel/SCSI routers to be important SAN components for years to come.

Crossroads Systems, Inc. and Chaparral Network Storage Inc. are important providers of Fibre Channel/SCSI routers.

Fibre Channel Raid
Fibre Channel RAID units are the core storage devices in SAN environments. Fibre Channel RAID units consist of Fibre Channel hard drives (from vendors like Seagate and IBM), RAID controllers (from vendors like Mylex, an IBM company), and a physical enclosure, which provides power and hard drive connectivity.

Fibre Channel RAID units arent exceedingly different compared to SCSI-built RAIDs in terms of feature sets. Like SCSI units, high-end Fibre Channel units feature dual controllers for both load balancing performance and for redundancy. In a SAN scenario, it is important to have reliable cache coherency built into the RAID controllers in the event of a hardware failure. At the high end, we also expect to see additions like a large RAM cache to improve the performance of disk I/O requests, and a support for hot-swappable hard drives.

The EMC Clariion line of Fibre Channel RAID units is popular for midrange SAN implementations.

SAN Software Managers and Tools
SAN management software is still an emerging product category, despite the fact that it is crucial for long term SAN management. The biggest problem with trying to manage a SAN, is that companies not only have to deal with typical network issues like connectivity and device management, but they also need to deal with traditional storage management issues like volumes, LUN management, and quotas. Future articles will cover the different management offerings and how each fits into a corporate IT network.

Veritas Software is considered the market leader in the space of storage management, and thanks to their comprehensive line of backup/recovery, clustering and replication, and file and volume management products, Veritas is the only major software vendor that can even claim to provide an end-to-end storage management solution for their customers.

Some of the challenges that lay ahead for SANs are obstacles that have already been solved in IP based networks. Over the next few years, we should expect to see device management comparable to the SNMP management solutions that are already available for IP networks. For this to happen, Fibre Channel switch vendors will have to settle on a standardized management interface from which all of their products can be managed.

Another major concern that will develop as we move on towards IP SANs will be the need for a new, scalable naming service to replace the simple naming service currently used in SANs. iSNS (Internet Storage Name Service) is currently making the rounds in the IETF, and it is expected to eventually become the new naming standard for SANs, and may provide the scalability and reliability of its IP-equivalent DNS.

Like IP networks, the day-to-day maintenance and troubleshooting of SANs requires powerful analysis tools that can sniff the wire and find transmission irregularities. Finisar Corp. is the leading developer of Fibre Channel analysis tools. The Finisar GT and GTX Analyzer is used to design, debug, and service SAN systems.

Besides offering protocol analyzers, Finisar also offers software products that analyze complicated SCSI I/O traffic over SANs, Bit Error Rate measurement tools, and system-level fault injection for SAN system testing and troubleshooting. The Finisar tools are used in many interoperability labs and are very useful in trying to diagnose Fibre Channel problems.

SAN vs NAS

There is much confusion surrounding the differences between a SAN and a network-attached storage, or NAS device. A NAS device is a self-contained, autonomous storage appliance connected directly to a network. Unlike SAN, which operates at a block level, NAS is a file oriented storage solution, which functions like traditional file servers in an IT infrastructure.

What is NAS?
The storage resources of a NAS device are accessed via mapped network drives which talk to servers and clients through the NFS (network file system) or CIFS (common internet file system) protocols, which are run over the IP protocol. The following diagram illustrates how NAS serves clients.

NAS is very simple to set up and maintain. The thin server technology used by most NAS devices is easy for network administrators of any skill level to understand and is very reliable. However, NAS is not a replacement for SANs.

For one thing, as more NAS devices are added to a network, their sheer number can become unwieldy. While some NAS devices have the ability to scale to several gigabytes in size, a well-designed Fibre Channel SAN can scale to accommodate terabytes worth of storage. As NAS use proliferates throughout a network, an IT manager has no option but to add more NAS units. Although an individual NAS device is easy to manage, it is extremely difficult to globally set parameters like security levels or application access to all NAS devices simultaneously throughout a corporate network, a crucial flaw that we wish NAS vendors would fix.

Overall, NAS is a great solution to centralize files on a workgroup level, but for companies that want enterprise-wide storage resource centralization for their distributed systems, a SAN is the only viable answer.

Differences Between SAN and NAS: File Level vs Block Level Protocols
The basic technical difference between SAN and NAS lies at the communication protocol level. While NAS communicates via NFS and CIFS Fibre Channel, SANs transmit data over FCP (Fibre Channel Protocol).

As the name implies, File Level protocols transfers data from storage units to servers in the form of files. Unlike a SAN, NAS solutions have their own file systems, which they manage independently within their storage enclosures. Although thin server units in charge of their own file system management and user authentication are convenient and typically easy to manage, a NAS unit can become a serious bottleneck in high transaction environments. (See our discussion of NAS performance below).

In the case of Fibre Channel, data is delivered in device blocks the same way an external RAID array would deliver data to an attached server. In a SAN environment the middleman, a thin server unit that typically manages NAS, is eliminated. Furthermore, since a SAN doesnt have to use IP to transfer data to the servers, the conversion of data blocks into IP packets (which is done in NAS) doesnt have to take place, and this reduces latency.

SAN and NAS Together
So, what is the role of network attached storage in conjunction with a SAN? Contrary to many beliefs, NAS is not replaced by SANs. Part of the confusion between these two technologies is due to the fact that both SANs and NAS have the ability to centralize data. NAS allows users to share data as a single files in a single data repository, leveraging networking technology (Ethernet) that virtually every company has implemented over the past decade. Since NAS moves storage traffic off of the SAN and onto IP networks, IT managers can use NAS to reduce the pressure in scaling their SAN infrastructures beyond their existing means, saving some infrastructure cost, though SANs by nature are extremely scalable. In its current state, SANs are best suited to serving the needs of transaction-intensive application servers, while NAS (since they dont require extra infrastructure) are best suited for the storage needs of low end workstations and desktops.

If NAS is cheaper to implement and has similar storage centralization capabilities, why should we bother to go through the painful process of SAN implementation?

Answer: Performance.

For performance reasons, most IT managers would not want to run disk-intensive applications on a NAS device across the network. Some applications, such as databases, work best when the database application has direct high-speed access to their directories, data and log files. NAS works well for file server access in most situations, but an organization should still use traditional server-attached or SAN storage subsystems to run disk-intensive applications such as transaction processing.

Applications of SAN Technology

Storage Consolidation
A major benefit of SANs is the consolidation of storage resources. SAN software and hardware have the ability to provide a centralized storage solution for servers. Interoperability issues due to operating system incompatibilities (most OSs dont like sharing storage with each other) and file system incompatibilities make the sharing of storage resources a difficult proposition, but the emergence of advance storage virtualization and management packages will eventually make the heterogeneous SAN a reality. Future articles will explain in-depth the challenges of building mixed SANs and the available solutions.

LAN-Free Backup
LAN-free backup first came into existence over 2 years ago and to this day, is still one of the biggest selling points of Fibre Channel SANs, especially in the workgroup to midrange class networks. As the name implies, LAN-Free backup moves backup traffic away from IP LANs and onto Fibre Channel SAN links. Another important feature of these products is that they facilitate the sharing of expensive tape backup libraries and autoloaders.

Two major vendors selling LAN Free backup solutions are Veritas Software with their NetBackup solution (with the Share Storage Option) and Computer Associates with their ARCserve Backup.

In tests, both of these solutions were able to move backup traffic away from our IP network and onto our SAN. Both of these solutions also featured intelligent management software that was able to specify which server had control of our shared tape library. A key component in any shared storage solution is an intelligent media manager, which not only keeps track of data, but also knows where that data came from. Without intelligent media management, the danger of servers writing over each others tapes is very real, and potentially deadly if the need to do a full data restoration ever occurs.

Serverless Backup
The reality of 24/7 IT shops has made Serverless Backup an enticing option. In a “Serverless” backup scenario, the CPU cycles that are normally burned doing a network backup are offloaded to intelligent SAN components (most often done by adding intelligence (an extra CPU) to SCSI/Fibre Channel router units).

On a SAN using Serverless backup, a physical volume can be ordered to back itself up or self-initiate a backup and tell other devices on the SAN that the physical device is unavailable, and any modifications made to its files will have to be temporarily recorded elsewhere until the backup is complete. This allows backup to take place alongside regular user activities. The high bandwidth typical of SAN networks shortens the time necessary to run a backup and to merge changes made to a volume after its backup is complete.

When devices on a SAN have this level of intelligence, they can operate in conjunction with SAN management software to do other operations on data besides mere backup. For example, storage devices can migrate their own data according to predetermined migration rules without having to wait for a server to initiate migration. A RAID system can migrate little-used files or data to archival storage. A tape library can notice if a file or block of data is being heavily used and migrate it to faster storage. All this activity takes place without input from administrators, servers, or users, freeing up server resources.

It also means that the SAN is not dependent on servers for performing housekeeping tasks. Servers are merely SAN storage resource access points for users and administrators.

Serverless backup typically uses “snapshot technology” to take a digital image of a RAID subsystem, which the Serverless backup components can then backup to an offline storage unit like a tape library. The use of the snapshot enables the servers, which are still utilizing the live data on the RAID subsystem, to continue to use that data without interruption, while the Serverless backup components quietly direct data through the SAN from the disk arrays directly to the tape unit, without going through the server. With this combination of technologies, IT managers can finally backup important “nonstop” data (which is required to be highly available), without having scheduled downtime or server performance degradation.

Legato, Computer Associates and Veritas all have Serverless backup solutions.

High Performance Caching (using SSD)
High performance storage caching is an emerging market that focuses on pushing up the performance of ultra high-end applications like enterprise-class databases. Well see these high-end storage caching units placed in front of SAN-enabled database clusters, allowing IT managers to boost overall performance of the clusters, provided the Cache hit ratio (I/O requests fulfilled by cache / Total number of I/O requests) is high. It is unlikely that this technology will be implemented in low to mid range shops anytime in the near future.

SSD (Solid State Disk) storage units that are built out of high performance RAM are being pushed as the top caching repository solution. SSD can support data throughput rates and IOPS (input output per second) several times faster than anything possible in the hard drive market, but this performance comes at a significant price. For example a RAM-SAN 8GB solid state, fibre channel drive from Texas Memory Systems has a list price of $50,000.

In closing, this wraps up our first foray into the land of SAN, and we hope it was informative. We expect to dive deeply into many other SAN technology areas in the future, as highlighted throughout the article. If you want to give us some feedback or share your successes or struggle with implementing SAN technology, let us know in our community forums.

Vendors to Watch

The world of SANs will continue to evolve over the next few years. The following vendors will be instrumental to the expansion of the SAN market:

SAN Storage Solution Providers

• EMC (35 Parkwood Drive, Hopkinton, Massachusetts 01748, 508-435-1000, www.emc.com) makes large scale (Symmetrix) and mid-range (Clariion) SANs with support for multiple servers and a variety of operating systems including multiple flavors of Unix and Windows NT/2000 simultaneously.
• IBM (New Orchard Road, Armonk, NY 10504, 914-499-1900 www.storage.ibm.com) makes their own SAN systems called the Enterprise Storage Servers. The systems all support multiple servers and operating systems simultaneously, and are designed for scalability to deal with unpredictable growth requirements.
• Compaq Computer Corp.(20555 State Highway 249, Houston, Texas 77070 www.compaq.com) Have solid SAN offerings ranging from low to midrange LAN free backup solutions to high end data center class solutions.
• Hitachi Data Systems (750 Central Expressway, Santa Clara, CA 95050, (408) 970-1000 www.hds.com) provides end-to-end SAN solutions with their Freedom Data Networks (FDN) supporting open architecture, multiple platforms, and “freedom of choice” for data-centric enterprise networks. FDN includes storage systems, switches, hubs, management software, and services.
• XIOtech (A Seagate Company) 6455 Flying Cloud Drive, Eden Prairie, MN 55344, 952-983-3000 www.xiotech.com) Their Magnitude SAN comes with a server and a suite of SAN virtualization and management software, and a fibre channel network with RAID controllers. The systems are fully configured at the factory, ready for the customer to connect to their network. The systems are true SANs with expandability and the capability of supporting multiple application and file servers.
• TrueSAN (60 S. Market St., Suite #1050, San Jose, CA 95113, 877-GO-TRUESAN www.truesan.com) is an aggressive small company that makes setting up a SAN as painless as possible with their SANDesigner web-based configuration tool. Written in Java, SANDesigner lets the customers figure out what storage resources should be included in their SAN. The company also provides their Paladin SAN solution. Paladin SANs can include WAN connectivity, optical interfaces, integration with NAS, and file management software. Like all SANs, the system is scalable so organizations can start with just their immediate needs and then expand the system later on as they grow.
• Dell Computer Corp. (One Dell Way, Round Rock, Texas 78682 www.dell.com) Primarily provides midrange NT/Windows 2000 based SAN solutions which work well with their PowerEdge Servers and other Intel based competitors.

Fibre Channel Switch Vendors

• Brocade (1745 Technology Drive, San Jose, CA 95110, 408-487-8000 www.brocade.com) is a maker of Silkworm fibre channel switches. Brocade sits at the top of the Fibre Channel Switch food chain and is OEMed frequently.
• Gadzoox (5850 Hellyer Avenue, San Jose, CA 95138, 408-360-4950 www.gadzoox.com) Competes with Brocade using their Capellix switches. They are also known for their Gibraltar hubs, which are found in low-end SAN solutions.

Host Bus Adapter Vendors

• Q Logic Corp. (26650 Laguna Hills Drive Aliso Viejo, CA 92656 (800) 662-4471 www.qlogic.com) Their SANblade host bus adapters are popular HBAs and Q Logic has expanded their product line to include Fibre Channel Switches (they are among the first vendors to ship a 2Gbps Fibre Channel switch.)
• Adaptec, Inc. (691 South Milpitas Blvd. Milpitas, CA 95035 408.945.8600 www.adaptec.com). They sell Fibre Channel Host Bus Adapters and they are starting to enter the external storage market with their Fibre Channel RAIDstation product line.
• Emulex Corp. (3535 Harbor Blvd. Costa Mesa, CA 92626-7112 Phone: 800-854-7112 www.emulex.com) Their LightPulse brand of fibre channel HBAs are very popular and in the near future we can expect to see Emulex releasing HBAs for the new iSCSI (storage over IP protocol). Emulex also produces Fibre Channel hubs and were among the first to demonstrate 2Gbps Fibre Channel products.

Software Vendors

• Tivoli (9442 Capital of Texas Highway North, Arboretum Plaza One, Austin, Texas 78759, 512-436-8000, www.tivoli.com) makes a suite of software used by many SAN system vendors. The flagship, SANergy is a virtual file system that eliminates the one-to-one relationship between SAN-connected computers and SAN-based disk volumes needed by those computers. It allows computers running different operating systems to share the exact same disk volumes at the same time.
• Veritas (1600 Plymouth St., Mountain View, CA 94043, 800-327-2232 www.veritas.com) Their SANPoint Direct management software works above the file system to allow multiple Windows computers equal file access to storage volumes kept on a SAN. Veritas is best known for their file system and for their Disaster Recovery/Backup solutions with work with multiple OS platforms and was among the first to offer a LAN free backup solution.