* Posts by Erik Smith

3 posts • joined 11 Oct 2011

Fibre Channel over Ethernet is dead. Woah, contain yourselves

Erik Smith

Re: iSCSI dead ? FC dead ? FCoE dead ? But Ethernet is alive !

Outside of your comment regarding multi-pathing I agree with you. Especially with regards to the Italians that, for all intents and purposes, drove FCoE through the FC-BB-5 standards process. There were a few others who were heavily involved and made important contributions but (IMHO) I think FC-BB-5 would still be debating things like "SPMA versus FPMA" if it weren't for two Italians in particular.

With regards to multipathing, I do not agree that iSCSI and FC/FCoE require different multipathing software (e.g., PowerPath). The MP stuff operates above the transport layer in the storage stack.

Erik Smith

What about Blade Servers?

Disclaimer - I work for EMC and have spent the past 7 years working on FCoE.

While I would agree that end-to-end (Server to Storage) FCoE never achieved widespread adoption, I disagree that FCoE is dead. Both HP blade server and Cisco UCS-B series customers use the protocol heavily and there are some compelling reasons for them to do so.

I also disagree with the notions that:

1) FCoE somehow legitimized IP Storage. They have been evolving independently of one another.

2) Enterprise customers are moving away from FC (in general). I've explained my reasons here: http://brasstacksblog.typepad.com/brass-tacks/2015/05/fibre-channel-is-better-than-ethernet.html

I also think DCB is merely a distraction for IP Storage. It adds a ton of complexity to the end-to-end configuration process and the value it provides is not significant enough to justify the extra complexity.


Mixing network traffic types on Ethernet

Erik Smith

A couple of minor points

I have a couple of minor points:

1. The statement, "...FC MTU is 1440 bytes..." should be 2240.

2. The statement "When an Ethernet frame is received on a Switch, it is placed into a memory location and waits for forwarding. For storage traffic this isn’t acceptable since the end-to-end delay should be as low as possible to ensure that storage throughput is fast. The Ethernet Switch is configured to immediately service the buffer that contains storage data as well as to forward the frame at the next interval." >> I’m not sure what is meant by this, FCoE Frames are routinely stored in a buffer and will be forwarded when bandwidth is available. As Greg mentions later, ETS (802.1Qaz) ensures that each priority is allocated a certain amount of bandwidth and in cases where the bandwidth is being fully utilized, or there is upstream congestion, FCoE frames will be stored in a buffer (sometimes for extended periods of time)..

Regards, Erik


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