iSCSI is actually a protocol and not a specific product like FalconStor. FalconStor is a virtualization metadata server solution where iSCSI is a method of using IP networking infrastructure to provide block-based access to storage arrays. iSCSI is very unique in that SCSI commands can be routed via a "client-server" environment over IP, just like direct attached storage devices. The goodness here is that using IP NICs to access storage is much cheaper than using expensive Fibre Channel switches and HBAs. The problem to date with doing this however is a lack of products on the market, limited availability of TOE devices (TCP/IP Offload Engines) that provide hardware based IP stacks, enabling iSCSI communication with less CPU overhead on the client application server.
One approach I do like in this area today is the iFCP protocol. iFCP passes FCP Fibre protocol messages over IP. The nice part about this is you can use existing Fibre SANs and connect separate SAN islands together over the Internet. The name server information from the remote SAN is copied to the local SAN and IP to WWN end-node address translation is done in the iFCP bridge. This makes the remote fabric look to the local fabric nodes as if it's in the SAME fabric. Things like remote replication between storage hardware over IP become easy like this.
iSCSI is still a protocol in flux and until standards have been around a while, interconnection and intercommunication of vendors products may be difficult. I still say Fibre SANss are the best way today for high performance block access to storage. Future technologies like DAFS over VI, and InfiniBand are coming. 10GB Ethernet will have a major impact in the speed of iSCSI-connected storage so the performance gap will soon close rapidly.
I'd really rather not get into the pros and cons of specific products, as I need to be unbiased as possible in my answers here. I have used FalconStor in the past and I can say it's a rather nice solution for in-band virtualization of disparate storage arrays by multiple vendors into a pool. It provides for investment protections for prior storage purchases. It also provides for remote mirroring of LUNs in the pool to remote FalconStor pools. That's pretty cool.
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This was first published in December 2001