Top Dos & Don'ts of iSCSI

A look at the keys to success and failure for iSCSI storage networking

January 19, 2008

7 Min Read
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iSCSI is coming into its own. The technology that enables storage gear to directly attach to Ethernet LANs in defiance of Fibre Channel has moved from the early adopter to the implementation stage.

Analysts wax bullish on iSCSI's prospects for 2008. Market researcher IDC predicts that the growth of VMware will pave the way for more iSCSI deployments than ever before; and analyst Nik Simpson of the Burton Group sees iSCSI making headway: All companies, no matter how large or small, are at least examining whether or not iSCSI is a good fit for them,” he notes.

As the hockey stick curves upward for iSCSI, the realities of implementing this storage networking option are rising to the surface, forcing adopters to look carefully at the pros and cons.

What follows is a look at the key "Dos" and "Don'ts" of iSCSI, taken from the experience of companies that have already "made the switch."

Do evaluate cost against alternatives
You may be pleasantly surprised. Standards-based systems are priced lower than products based on proprietary interfaces, and such is the case with iSCSI devices, which are built on a TCP/IP foundation.“We had some extra NICs [network interface cards] and a few empty slots in our Ethernet switch, so we did not have to buy a new switch when we deployed our new storage system,” explained Rachi Messing, VP of technology services at DiscoverReady LLC, a legal software services startup that relies on Compellent’s iSCSI products.

iSCSI is typically cheaper than Fibre Channel. While cost differences vary by individual company configuration, the hardware savings from iSCSI compared with Fibre Channel range from 10 percent on the low end to 50 percent at the high end, according to analysts and users.

According to a recent Enterprise Strategy Group report, for example, 40 percent of respondents to an in-depth survey on iSCSI deployment said they had reduced capital expenditures by 11 percent to 20 percent and 37 percent reported operational expenditures in the same range.

Figure 1: Source: Enterprise Strategy Group

In addition, small and medium businesses (SMBs) can often cut their software expenses with iSCSI as opposed to Fibre Channel. “What appealed to us about iSCSI was not only that we had an inexpensive storage solution, but also that applications such as data backup were bundled with the system,” stated Josh Huisken, IT manager at Intense Lighting, a California lighting supplier, who purchased a NetApo iSCSI system.Do make the most of easy installation

Twenty minutes -- that was how long it took the EqualLogic salesperson to hook the company’s PS iSCSI SAN into Assisted Living Concepts’s network. At that point, IT administrator Mark Hall was convinced that EqualLogic’s iSCSI products were right for his company, which also evaluated Fibre Channel and NAS solutions.

iSCSI is simple to manipulate because it was designed to plug into Ethernet networks, and many devices, including just about any type of network equipment, have those interfaces.

Do note the personnel requirements

One key to iSCSI's success is its accessibility to a wider IT audience than Fibre Channel addresses. If you don't have TCP/IP expertise in house, though, that may be a problem.

Thankfully, just about all IT technicians are at least somewhat familiar with TCP/IP, so iSCSI expertise is quite common. Conversely, few understand how to manipulate Fibre Channel. “Not only are Fibre Channel technicians hard to find, but also they are quite expensive to hire,” said Pat O’Day, chief technology office at BlueLock, a startup infrastructure-as-a-service supplier, using Lefthand’s iSCSI products.

Do consider your data requirements

Here's where your iSCSI investment might be justified. DiscoverReady LLC was founded in 2005 to help law firms manage the large volumes of data available for corporate cases. The company takes all of the information generated at the start of a case and uses various data-sifting tools to pare it down (usually by 50 percent, execs claim) to only the most relevant information. In June 2006, the startup installed Compellent’s iSCSI SAN to centralize data administration. “We started with about 8 Tbytes of data, we have 24 Tbytes now, and we expect to go to 48 Tbytes in the next 12 months,” noted DiscoverReady LLC’s Messing. “So far, the upgrades have been quite easy to complete.”At least part of the attraction of iSCSI SANs emanates from their support of commodity SATA disks drives, compared with the need for costlier Fibre Channel hardware. This feature can make it easier to install extra capacity as it's required. That said, though, lower-cost drives have a reputation for increased failure rates that must be weighed against the trade-off in cost and ease of installation.

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Don't use iSCSI for bandwidth-intensive applications

iSCSI now operates with 1-Gbit/s connections, which is fast enough for many SMBs. If a company needs more bandwidth, then Fibre Channel is the better option, at least in the near term.

“iSCSI vendors have been working on 10-Gbit/s products and expect to start shipping them later this year,” says Mark Peters, an analyst at the Enterprise Strategy Group.

Last year, vendors demonstrated 10-Gbit/s iSCSI products at tradeshows. Interoperability testing represents the next development phase. Still, as such solutions begin to ship, price may be a significant deterrent. Experts say 10-Gbit/s Ethernet ports and NICs cost 30 percent to 50 percent more than their 1-Gbit/s counterparts, which will slow adoption of the higher-speed SAN option.Don't expect robust management tools

iSCSI is simple to deploy and tends to run smoothly in many cases. If a company is looking for sophisticated management functions, other options may be more suitable. “iSCSI products come with monitoring and reporting tools, but they are a little bit light,” said Ed Bavais, IT network manager at Sabert, which uses EqualLogic’s products. “The tools could delve a bit more into network and processor usage so we get a clearer of what is happening with our transactions.”

Don't mix active and passive switch ports

iSCSI usually drops easily into an enterprise network, but there can be deployment issues. Because iSCSI is new, it doesn't always work with every iteration of Ethernet. “We had some active and passive Ethernet ports on our switch, and iSCSI would not work with that configuration,” explained Assisted Living Concepts's Hall.

Don't fret about vendor support

Riding the initial wave of any new technology represents a risk. Often the primary vendors are small startup suppliers with little to no proven track records. Initially, that was the case with iSCSI, but the major vendors are moving into the market and making an impact. The most striking example is Dell’s $1.4 billion purchase of EqualLogic in November 2007. “Just about all of the major storage vendors -- IBM, HP, Sun -- are moving to embrace iSCSI,” stated Burton Group’s Simpson. “Customer interest in the technology has become too great for them to ignore.”

Bottom line: If you buy from one of today's big iSCSI suppliers, don't worry that your mainstream iSCSI wares will become an in-house do-it-yourself project.

Don't expect Fibre Channel to fall by the wayside

iSCSI offers enterprises many benefits, but only 10 percent to 20 percent of companies have deployed iSCSI-only solutions, according to observers. Working with the Internet Engineering Task Force (IETF), Fibre Channel suppliers have developed a standard, dubbed RFC 3821, which allows Fibre Channel transmissions to run over TCP/IP networks. Their work is still in the proof-of-concept stage, but compliant products could begin to arrive near the end of this year.Separately, a group of vendors led by Cisco, including Intel, IBM, and Sun, have generated their own Fibre Channel over Ethernet (FCoE) spec that is aimed at enabling SAN traffic to be natively transported over Ethernet LANs. While FCoE won't be routable, it's garnered widespread interest as an alternative to iSCSI, and work to standardize it has been undertaken by the T11 committee of the International Committee of Information Technology Standards.

Fibre Channel’s most significant advantage appears to be its illustrious history and deep enterprise entrenchment. “Inertia is always a significant hurdle whenever new technologies emerge,” concludes Enterprise Strategy Group’s Peters. “Consequently, many companies are now content to continue to rely on Fibre Channel rather than take a look at iSCSI solutions.”

Have a comment on this story? Please click "Discuss" below. If you'd like to contact Byte and Switch's editors directly, send us a message.

Paul Korzeniowski is a freelance writer who specializes in data storage issues. He is based in Sudbury, Mass., and can be reached at [email protected].

  • Burton Group

  • Cisco Systems Inc. (Nasdaq: CSCO)

  • Compellent Technologies Inc.

  • Enterprise Strategy Group (ESG)

  • EqualLogic Inc.

  • IBM Corp. (NYSE: IBM)

  • IDC

  • Intel Corp. (Nasdaq: INTC)

  • Network Appliance Inc. (Nasdaq: NTAP)

  • Sun Microsystems Inc.0

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