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Experts: What's the buzz on iSCSI?

Maryann Tripp, Assistant Site Editor
SearchStorage.com wanted to get to the heart of the iSCSI buzz so we went to two of the top storage industry experts and authors: Tom Clark and Gary Orenstein. We first caught up with Tom Clark in Beijing, China where the topic of iSCSI and how it's going to play out topped the agenda. (Tom Clark

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is the director of technology at McData and author of "IP SANS: A guide to iSCSI, iFCP, and FCIP protocols for storage area networks.") Joining Tom with iSCSI insights straight from the show floor at Storage Networking World in Orlando is Gary Orenstein, vice president of marketing at Compellent Technologies and author of "IP storage networking - Straight to the core."

Tom and Gary weigh in on who should be implementing iSCSI, what a successful implementation would look like and what they're hearing from IT professionals about the cost of it all.

Editor's note: This Q&A is part of a larger Featured Topic, iSCSI: What it is, where it works.

SearchStorage.com: Where does iSCSI technology stand right now? And, where do you see it going?

Tom Clark: iSCSI has left the exaggerated claims/hype phase and is finding its place in real-world applications. Two significant gating items have been standardization, which was achieved this year, and endorsement by major vendors such as Microsoft. Given that Microsoft is providing iSCSI and iSNS client drivers as part of Windows 2003, it will encourage users to take advantage of block data over IP, particularly for second-tier and third-tier servers.

I think iSCSI will be an enabling technology for the broad middle market, which to date has had difficulty justifying investment in Fibre Channel SANs. iSCSI enables customers to reap the benefits of storage consolidation, streamlined tape backup, etc. at a much more affordable entry point. iSCSI will also provide a broader market for Fibre Channel SAN technology as it will put more customers into the SAN space and those customers will begin admixing Fibre Channel for higher performance requirements over time.

Gary Orenstein: iSCSI is approaching mainstream adoption. While 2002 was the year of early adopters, 2003 brought product introductions from major systems vendors and numerous well-documented user case studies. iSCSI will shortly make its way onto many 2004 storage requirements checklists.

As with all new technologies, it takes some time for both the vendor and user communities to get a handle on product and solution implementations. However, at the end of 2003 we have a range of hardware and software iSCSI initiators available, including Microsoft's inclusion of a Windows iSCSI software stack. We also have target systems available from large system vendors and innovative start-ups putting iSCSI creatively to use.

SearchStorage.com: What are you hearing from IT professionals about implementing or not implementing iSCSI into their current architecture?

Tom Clark: There is a high level of interest in iSCSI in the IT community, particularly as the economy continues in its doldrums. Storage problems haven't disappeared just because the economy is not cooperating. IT professionals are still looking for means to address [these problems]. The availability of iSCSI device drivers, iSCSI adapters and iSCSI-FC gateways (if I can plug the quite affordable Eclipse 1620, for example) now provides the components required to implement (and we've had more of those since the beginning of the year).

Gary Orenstein: Almost everyone wants to make use of iSCSI and its IP networking infrastructure for storage. It's rarely about "not implementing," but more about the right places for the technology at the right time. For experienced storage administrators with large Fibre Channel SANs, iSCSI helps them consolidate less expensive or remote servers to their centralized storage infrastructure. For green field opportunities, iSCSI provides an economical and easy-to-implement network storage architecture based on existing staff skill and resources.

SearchStorage.com: What are some of the common questions a manager/administrator should ask when looking to deploy iSCSI into their current environment?

Tom Clark: As with any SAN deployment, the customer must understand their application requirements.

  • Which applications will benefit the most from shared storage?
  • Where do I need to apply the greatest bandwidth (e.g., high-performance servers should probably be FC attached)?
  • What applications can reasonably run on gigabit or sub-gigabit bandwidth (iSCSI)?
  • How much can I save by bringing in, for example, Wintel or Linux servers via iSCSI to streamline backup operations and reduce administrative overhead?
  • The technology for both high end and medium-to-low end SAN solutions [is] now available. So, it's largely a matter of sizing the solution to the problem.

    Gary Orenstein: The questions depend on the implementation. For example, for server consolidation to centralized storage, some questions might include:

  • Do I have an IP and Ethernet network in place for my iSCSI traffic?
  • Do I want to segment that traffic on a separate IP network or use VLANs to logically separate the iSCSI traffic from my LAN messaging traffic?
  • Do I think I need TCP/IP acceleration in my servers? If so, are PCI slots available for the card? Will a software initiator be sufficient?
  • Do I want to make use of existing Fibre Channel or SCSI storage? If so, I'll need to consider an IP storage switch or router to handle the iSCSI to Fibre Channel or iSCSI to SCSI protocol conversion.
  • Do I want to purchase a new iSCSI target?
  • If purchasing an iSCSI target, what additional storage software services (backup/recovery, snapshot, policy management) do I want to have?
  • SearchStorage.com: When (or in what situations) should IT managers/administrators consider implementing iSCSI?

    Tom Clark: iSCSI is an economical solution for any medium-to-low performance server population. IT managers would deploy iSCSI for the same reasons they would want to deploy any shared storage: reduced administration, simply management via storage consolidation, covert labor-intensive backup operations to SAN-based backup. In terms of networking storage and servers together, iSCSI does the same basic job that Fibre Channel does with the caveat that it currently runs at lower bandwidth (1 Gbps vs. 2 Gbps for FC). Otherwise, it fits the same end user value proposition that FC SANs do.

    A significant advantage of iSCSI compared to Fibre Channel is that it accommodates stranded servers (across campus, regional or remote branch distances) for remote connection to data centers via standard IP networking. So even if a customers relies primarily on FC for SANs, iSCSI can complement an enterprise-wide storage strategy.

    Gary Orenstein: IT managers or administrators should consider iSCSI in a variety of situations such as:

  • Departmental installations where the lower cost and skill levels required for iSCSI make deployment feasible.
  • Connecting low cost servers (where expensive host bus adapters might not make sense) to centralized storage.
  • Campus situations where the widespread availability of IP and Ethernet networking makes iSCSI transport more feasible than Fibre Channel transport.
  • Installations requiring remote data transport. iSCSI, as a native IP protocol, makes this process relatively seamless.
  • SearchStorage.com: From the success stories that you have seen, could you list the characteristics a successful iSCSI implementation would exhibit?

    Tom Clark We have customers that are using iSCSI accelerators (e.g., Alacritech) and others just using iSCSI device drivers on traditional Gigabit Ethernet cards. An installation is successful if the host connectivity accommodates the server performance requirements. Since our products do wire-speed iSCSI protocol conversion, there's a lot of flexibility in mixing/matching iSCSI host connectivity to storage traffic needs. If the IP SAN solution meets performance requirements and the business objectives (e.g., results in reduced administrative costs), then it's a success for the customer.

    Gary Orenstein: A successful iSCSI implementation would include:

  • Use of networked storage for applications and configurations that could not previously benefit from a SAN.
  • Use of existing staff skills to leverage IP and Ethernet experience.
  • Tailored solutions to business needs. For example, use of software initiators where applicable complimented by TCP/IP acceleration adapters for high-performance needs.
  • Complementary storage to existing resources. For example, extending the reach of a Fibre Channel SAN by connecting low cost servers via iSCSI through an IP storage switch or gateway.
  • SearchStorage.com: We've heard a lot from vendors about how much cheaper iSCSI components are going to be than their Fibre Channel counterparts. But, we've also heard from disgruntled managers that that may not be the case. What's the real story here? Are there hidden costs to iSCSI?

    Tom Clark: Currently, the cost savings for iSCSI is in host connectivity. On the host side, the cost can range from essentially zero (free device drivers) to about $1K for high-end iSCSI adapters. This is a more economical attachment cost compared to the still ~$1500-$2000 for Fibre Channel HBAs. If you're using Fibre Channel storage, then there's the cost of the iSCSI-FC gateway. [In an] apples-to-apples comparison to Fibre Channel, iSCSI will always be more economical because of the reduced host connect costs. When you have native iSCSI on storage devices, even the cost of the gateway goes away.

    As with any storage implementation though, the real cost is not the initial hardware investment but the on-going management. So, how much a customer will save by deploying iSCSI or Fibre Channel really depends on how the technology put in place aligns with the customer business goals. A well-designed SAN with appropriate management tools keeps the recurring management overhead to a minimum.

    Gary Orenstein: While equipment costs are an important part of any storage solution, at the end of the day the true costs come in the day-to-day operations.

    From a broad market perspective, iSCSI components are likely to be cheaper than Fibre Channel because they will inherently benefit from the global deployment of IP and Ethernet networking. The research and development budgets, coupled with the sheer volume of IP and Ethernet components will likely keep iSCSI hardware costs well below those of Fibre Channel.

    But that is only the tip of the iceberg. Consider the cost of adding trained specialists for Fibre Channel compared to those for IP and Ethernet. Or, consider the ability to leverage a common IP infrastructure (even if it is logically separate) across both LAN messaging traffic and storage networking. Even with physically separate IP and Ethernet networks, all of the common parts can be shared such as cabling, Ethernet switches and IP monitoring tools.

    Effective iSCSI planning includes evaluating equipment purchases, but also reaching into organizational resources to see how much existing staff experience and IP and Ethernet equipment can be leveraged for the most cost effective solution.


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