iSCSI vs. FiberChannel

[spidey07]

FiberChannel storage area networks are a great advancement when it comes to mass storage frames. High performance (100 MB/s) is realized by switching the fiberchannel frames/data instead of using a shared bus architecture like SCSI. This way very large disk frames to the tune of dozens are terabytes and hundreds of volumes can be housed in a single managed device.

My rub is the cost of fiberchannel switches especially since this kind of pooling of resources using a high-speed LAN is nothing new. FC switches can run $2000 per port not to mention the expense of the blades in the disk frame. Gigabit Ethernet on the other hand is around $500 per port using fiber.

Seems to reason that with Gigabit ethernet so mature you could use the higer performing ethernet switches to replace or displace the FC switches. That is where SCSI over IP comes to play.

So, who will win the upcoming battle for SANs? 10 Gigabit ethernet is already out and sure to drive down ethernet costs yet again. To me iSCSI is a clear winner considering the existing network management tools available today, higher performance, and the ability to scale with IP.

Should be an interesting two-three years for stroage.

 

[SCSIRAID]

The key issues for iSCSI to move forward are:

1) The ability to boot... (TCP/IP in BIOS) - FC can do this today since card appears as SCSI device - Int 19/13 works
2) The availability of TOE equipped adapters to move TCP overhead off the host CPU - FC doesnt have this problem/issue

The longer iSCSI delays.. the longer FC has to get entrenched and drop the switch prices. The switch price is artificial and represents the lions share of the FC price problem.

By the way... Drives arent switched today... They us FC-AL - arbitrated loop and thus share the bandwidth of the 2Gbit channel. That wont necessarily true as time moves on though.

 

[spidey07]

<< They us FC-AL - arbitrated loop and thus share the bandwidth of the 2Gbit channel >>



You sure about that? The EMC 8730 frames I'm used to "bond" several switched FC ports into a logical channel, 4 for example and then those 4 links are insterted into the switch fabric or blade in a McData FC switch. Or you can assign one FC port on the frame to a particular volume or any number of flexible options.

You're right though. iSCSI needs to get the standards and issues resolved quickly. I'm doing my share by pressuring EMC and McData reps with "why in the heck would I keep buying your expensive switches when I can do it with gig ethernet". Hopefully they get the message cause the markups on FC gear is OUTRAGEOUS.

Nice to see someone paying attention to the match. I really just feel like fiber channel is just re-inventing the wheel of networks/ethernet.

 

[SCSIRAID]

Im not familiar with the EMC frames you are talking about but.... I would bet that the frame has more than drives in it. A SAN _controller_ would definitly connect to a switched fabric. If the frame was pure drives then you could still us a switch internal to the frame with a fabric port on the output side and FL ports on the side connecting to the drives. I would bet that its the first though.

To your comment : "I really just feel like fiber channel is just re-inventing the wheel", I think that goes both ways. Ethernet is a clear winner in fabric management. FC is the clear winner in storage management tools and optimization for storage transport. FC is way ahead in merging everything together and has been at it for at least 3 years. The "holy grail' of a single network running Com and Storage is just not real in my opinion. I believe there will always be two connections to the box... one for storage and one for comm. They could however be the same fabric type...(ie both ethernet). OS's dont give you much capability to get 'deep inside' their TCP/IP stacks and do the proper offload to efficiently enable both comm and storage access. TOE is easy for storage alone since you dont hit the OS TCPIP stack (you are a disk device type not a comm type). Not so easy to merge.

 

[454Casull]

I shudder to think how much this must cost

 

[spidey07]

about 160K list...90K if you work the salesman.

that's the problem with fiberchannel. to friggin expensive. I could purchase a cisco switch with WAY MORE FUNCTIONALITY AND WAY MORE PERFORANCE for 1/2 the price.

btw...brocade is cornering the market on FC. Most gear is simply re-badged brocade stuff. EMC, compaq, HP, hitachi...rebadged brocade.

<edit> this is about as advanced as the ancient cisco 5500 switches. Yeah, those were end-of-life about 4 years ago.