iSCSI Technology

The concept of pushing SCSI, or block oriented storage commands, over a serial interface is not really new technology. FC, IEEE-1394 and USB have been doing this for a number of years already. The major difference between these buses and the buses that carry TCP/IP is that IP based buses were never intended to be used as storage transports, which require sequenced ("in order") delivery, guaranteed timing, and robust error correcting. The rise in attention to iSCSI is attributable to the speed improvements that have been made, and that are planned, for network signaling. The increases from 10/100 Megabits per second (Mbs) to Gigabit Ethernet (GbE), and eventually 10 GbE and beyond, make the Ethernet physical connection as fast as FC.

iSCSI (and other IP based storage initiatives) represent a change in direction for storage attachment to servers and SANs and this could possibly change the assumptions around the deployment of storage. The installation of a SAN forces IT departments to consider not only infrastructure but also technical abilities of the staff required to support a new storage model. Most storage installed today is directly attached to the servers that use the resource. Installing a shared storage system will require IT staff to learn new concepts such as fabrics, Logical Unit (LU) masking and mapping, and resource allocation. FC has been the connection to date that empowered this storage-thinking shift. iSCSI is seen as a method to implement storage-networking technology without the additional cost of training staff on FC.

Initial devices that have been announced using iSCSI include tape controllers, iSCSI switches and protocol bridges (storage routers). The market for storage devices (specifically large SAN or NAS) that will use iSCSI is not large at this point, and many major manufacturers will wait on including the new interconnect since it does not radically change the market they service. Once the nuances of iSCSI are worked out in the initial products and interoperability tests, manufacturers of end-node devices (storage subsystems, tape systems, large RAID devices) will begin to build iSCSI as native interconnects. Before that occurs, however, it will be the job of protocol routers to provide connection and translation between iSCSI and other protocols such as FC Protocol for SCSI (FCP) and parallel SCSI. Following any volume in products that support iSCSI natively, the job of the protocol router will continue as a storage network expansion product, divergent bus interconnect, and protocol management service appliance.

Crossroads iSCSI Demonstration At Storage Networking World

Storage Networking World has become the premier event for the Storage industry, consistently focusing on end-user education and technical excellence. For this reason Crossroads Systems decided to introduce the work it has been doing on iSCSI, and bring to bear the potential of a highly educated audience for our assumptions and development. Crossroads has focused on the basics of iSCSI, preparing for robust command delivery, protocol conversion and device handling while also preparing its development on security, discovery and acceleration, as those topics continue to develop in the iSCSI specifications. Crossroads' partners in this demo included Compaq, Intel, Microsoft, and StorageTek. These companies and Crossroads share a common vision to make iSCSI interoperable and reliable for ensured success as an interconnect for storage networking.

The iSCSI demo provided an opportunity for Crossroads to deliver a level of iSCSI storage routing on par with proven leadership in other storage routing protocols. Crossroads pioneered the storage routing market, and understands protocol conversion. Crossroads knows how to ensure interoperability in a market where "Vendor Unique" often can mean that other devices won't always operate as expected. Unlike many companies who are starting from scratch, Crossroads is building upon 5 years of success in understanding Fibre Channel and SCSI, and sees iSCSI as an additional protocol to service with a proven level of quality.

The iSCSI demonstration builds not only on Crossroads' understanding of storage protocol conversion, but also on that of established industry leaders. For example, Compaq is the leader in Enterprise and Storage systems integration. Intel directs the market in networking and intra-system communication, showing best in class GbE system design and switch technology. Microsoft, with Windows Server platforms, continues to push its understanding of storage and management, to the benefit of IT managers. And finally, StorageTek is the undisputed leader in storage backup hardware. These long-time friends of Crossroads are excited to be involved in developing interoperable and reliable iSCSI products.

The iSCSI Demo Development

iSCSI will not automatically win applications in Enterprise storage or SAN deployments just because it is the newest technology. When Fibre Channel was first introduced, it did not displace SCSI because it was faster or easier to implement. Crossroads made its mark in the industry by delivering interoperability that bridges these two divergent buses. Similarly, Crossroads believes the benefit of the newer technology, iSCSI, will lie in the ability of IT managers to implement the developments without having to throw out existing investments in equipment. The iSCSI demo concept presented a simple storage fabric using off the shelf parts (demonstrating interoperability) and the Crossroads iSCSI router, based on Intel's iSCSI SourceForge project. Microsoft's iSCSI StorPort driver runs on .Net Server Beta, and Intel's iSCSI HBA and Miniport drivers run on a Windows 2000 Server to provide host connectivity. Standard SCSI ports using un-modified Crossroads SCSI protocols connect to simple disks and a StorageTek or Compaq tape library. Backup functions were provided through Windows Backup on the Windows .Net Server host, backing up the local iSCSI drive as well as the network-mounted iSCSI drive from the Windows 2000 host.

This configuration demonstrates the utilization of the iSCSI connection and protocol for SCSI tape library, and disk connection conversion.

Demo Basics

The Windows .Net Server Beta was the platform for one iSCSI connection while also acting as the backup server for both hosts. All access to the library occurs over the iSCSI connection, once converted from SCSI. The Windows 2000 Server's iSCSI disk was shared through Windows Networking, and was mounted as a Networked Drive in the Windows .Net Server host. Backup took place from the Windows .Net Server, for both its local iSCSI disk, and the iSCSI disk exposed by the Intel iSCSI HBA.

The following steps were shown in the demo.

1. Windows Backup starts, and pre-selected directories for both hosts are highlighted for action on the Windows .Net Server host.
2. Start Backup is selected, causing SCSI commands to direct the tape to mount, rewind, and position to begin the backup. Verification of files on backup is turned on for this operation.
3. After positioning of the tape, the files are backed-up from the Windows .Net Server, and then the Windows 2000 host proceeds. During this operation, Performance Monitor on both hosts shows activity on the iSCSI-mounted disks. SCSI commands being converted by the Crossroads iSCSI router are sent to the SCSI disks.
4. During backup, the Intel iSCSI HBA monitor tool demonstrates SCSI command packets traversing over the Windows 2000 host.
5. Once finished, backup of both disks is shown as complete in Windows Backup, with final completion status being posted.

Crossroads Commitment

Crossroads will continue to build on its understanding of protocol conversion and storage routing for iSCSI and other new storage opportunities as these technologies develop. Crossroads understands the market need to drive the adoption of iSCSI and believes that successful adoption of iSCSI will not come without robust interoperability. The Crossroads iSCSI demo focused on providing a strong example of that interoperability for the industry. Interoperability will be the center of Crossroads attention as iSCSI development continues.

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