April 03, 2001, 3:33 PM — When Rick Nelson went to work at EchoStar/DSSH Networks in Denver in 1997, the senior IT architect had a design for a storage-area network, but unfortunately, storage vendors did not have the hardware to make that design a reality.
But the storage needs of the satellite services company continued to grow in size and complexity until a SAN became a necessity. Nelson learned that Computer Networking Technology (CNT) of Minneapolis was working with storage powerhouse EMC on a way for customers to use EMC's Symmetric Remote Data Facility (SRDF) software to replicate data over several hundred miles.
That was exactly what Nelson needed because EchoStar was building a disaster-recovery center in Gilbert, Ariz. CNT uses proprietary software to convert SRDF data frames to IP packets, which are then sent over the WAN using CNT's optical extenders.
In phase one of the SAN project, EchoStar experienced a 500% improvement in the time it took to do local tape backup. Even more importantly, EchoStar could send key company data to the disaster-recovery center, including information about EchoStar's five million customers, a data warehouse that is used for strategic analysis, Oracle Financials, and commission information about EchoStar's dealers.
Nelson says the new SAN is a vast improvement over the company's previous method of protecting its data, which consisted of "making a copy of our tapes, putting those tapes off-site and praying that nothing happens." As Nelson says, when your company's storage requirements are growing at the rate of 450% per year, and you expect to be managing 40 terabytes of storage by the end of 2001, that type of solution just won't cut it.
EchoStar is one of a growing number of companies taking advantage of new technology that can extend a SAN over long distances.
The business drivers behind this demand for longer range SANs fall into two categories: metropolitan-area networks and WANs.
First, the demand for midrange metropolitan-area networks is coming from financial institutions and large companies that want to move data out of what they consider to be dangerous areas -- areas susceptible to floods, earthquakes and other natural disasters.
For example, financial institutions and financial services companies in New York typically want to move data from Manhattan to New Jersey or neighboring states to protect it from disastrous power failures. Initially, these institutions solved the problem by shipping the data via tape to New Jersey, but when the data explosion of recent years began, this procedure became impractical, and these companies looked for another way.
They found it in the form of extended SANs -- that is, SANs that could be extended with optical networking equipment so they could cover distances of up to 120 kilometers, rather than being restrained by the 10 kilometer Fibre Channel limit.
These devices come in two forms -- extenders or repeaters, such as the OptiLink 2000 by Finisar; and wave division multiplexers (WDM) and, more recently, dense wave division multiplexers (DWDMs) from ONI Systems, Nortel Networks and ADVA Optical Networking.
Although there is currently much more activity in the metropolitan-area market than in the WAN, over time the demand for transporting storage over WANs is expected to far surpass metropolitan networks, especially when the data is transported over IP, says Steve Duplessie of the Enterprise Storage Group.
He says that transporting storage data over IP is one of the most significant trends in storage today. "The reason this is an important technology is that ultimately it's going to let users have a choice -- a choice between building storage networks on an Ethernet infrastructure that they already have or building a separate storage network based on Fibre Channel. Up until now there has been no choice for users -- they had to build a Fibre Channel-based storage network."
IP storage networking offers several advantages to users. These include protecting more data than was possible before, deploying more information anywhere, utilizing users' investments in existing IP network infrastructures and supporting WAN distances.
There are currently three different ways to transport storage data over IP:
SCSI over IP, supported by Cisco, Adaptec and IBM.
Storage over IP, supported by Nishan Systems.
Fibre Channel over IP standard, supported by CNT, Gadzoox, Cisco, Vixel and Lucent.
SCSI over IP works by having a host-resident agent encapsulate SCSI data in an IP packet, and tunneling that encapsulated packet through the TCP/IP stack. The encapsulated packet then goes out to the IP network through the network interface card. At the receiving node, the IP packet is unwrapped by an external router and converted back into SCSI data.
