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ISCSI goes where FC dares not |
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The Storage Networking Industry Association (SNIA) has announced that the iSCSI Management API (IMA) will shortly be submitted to its members for approval before heading to the American National Standards Institute for final ratification.
Big deal, we hear you say. These standards get stuck in approval processes for eons, right? Not this one, it seems. It's being "fast-tracked" through all the red tape by heavyweight backers including IBM, EMC Corp., Hewlett-Packard Co., Brocade Communications Systems Inc., Cisco Systems Inc., Adaptec Inc., Emulex Corp., QLogic Corp. and many others.
The aim of IMA is to speed up adoption of iSCSI by enabling interoperability between iSCSI host bus adapters (HBA) and iSCSI management applications through a standard interface, according to Matt Brissee, technical strategist in the office of the chief technology officer at Dell and vice chairman of the board of directors for SNIA.
"ISCSI is touted as easy to use, but when you look at a data center, there are different operating systems, different vendors, different graphical user interfaces -- for iSCSI to really take off, we have to make sure everyone writes to the same API," Brissee said. He noted that to this day, FC HBAs are still incompatible with each other.
A single application program interface (API) would allow users to mix iSCSI HBAs from different vendors without worrying about compatibility. It also eliminates the need for iSCSI management applications to write custom code for different iSCSI HBAs, making it easier and quicker to support multiple iSCSI HBAs from different vendors. And it drives down integration and test costs, speeding up the time to get products to market.
The majority of iSCSI installations so far use standard network interface cards and an iSCSI software initiator, but this will change, experts say. Tom Major, vice president of marketing at LeftHand Networks Inc., which has over 1,500 implementations of its IP SAN array, noted that most of the setups today are small enough that they don't have heterogeneous management issues. "But as iSCSI speeds increase and the size of installations gets larger, it will become necessary to use iSCSI HBAs," he said. "It's nice to see standards ahead of the market for a change."
"Today, iSCSI doesn't take up too much CPU power. But down the road, as iSCSI moves upstream, users will need the offload to make sure hosts don't lose too many cycles," said David Hill, principal analyst with Mesabi Group LLC, an IT consultancy.
iSCSI advocates think that IMA will ensure iSCSI avoids the biggest complaint about SANs today -- which is parts that don't interoperate -- and in doing so stands a healthy chance of eventually replacing FC.
iSCSI has some clear advantages in it favor
First, it uses TCP/IP, which has existed for over 20 years and is the granddaddy of all standards in the networking world. Combine this with SCSI --which has also existed for decades and is well understood in the storage world -- and you get a rock-solid storage networking protocol.
Second, the iSCSI protocol continues to be vetted through different bodies to ensure that everyone is complying with the same specification. We've lost count of the number of iSCSI interoperability plugfests that have taken place, and the New Hampshire Interoperability Labs is wondering what it ever did before iSCSI.
Last, Microsoft's entry into the space with its software initiator has validated the market and made it accessible to all.
SMI-S update
SNIA's success at pushing standards is apparent in the broad adoption of the Storage Management Initiative Specification (SMI-S), which lets users integrate storage devices together with a variety of different management tools. SMI-S 1.1 will be ratified at the end of April and includes support for NAS and iSCSI arrays.
SNIA also announced MultiPath Management API (MMI) and increased functionality for Disk Data Format (DDF). MMI allows a management application to discover multipath devices, and the associated local and device ports, instead of requiring proprietary multipath drives from each vendor. Support for RAID-6 has been added to DDF, which is also on its way to ratification.
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