Connectrix FC switches

Question

How do I calculate the daily maximum Bandwidth (utilized) of an 16 port FC switch at 2 Gbps in the environment ??

RRR · Accepted Answer

Bandwidth as in MBps ?I've seen (warning message in ECC) as much as 200MBps on a single 2.125Gb port, so the math tells me 60 x 60 x 24 x 200 = 17.2TB on a single day.But on FC layer 1 there's the 8b/10b encoding/decoding, so I'd say this 200MBps (which I actually did see) is about 170MBps in user data.Having said this, you need sufficient spindels in your storage system to sustain this kind of throughput, so with only 5 spindels you're not getting anywhere near that value. An EMC PSE once told me to calculate 10MBps per spindel, so to get 200MBps you'd need at least 20 spindels.Source: http://en.wikipedia.org/wiki/Fibre_Channel_8B/10B_encoding

Summi1 · Answer

Why 200 MBps ?? I mean to say we are having a port which can support upto 2Gbps so how did you get 200 MBps?? Is there a way to calculate it?? Is it a spec on every switch where I should look at..Please let me know.

sfuhrman · Answer

The 8b/10b encoding overhead is already built in to the fibre channel spec, so you can in theory get 200 megabytes per second of payload. Actually if every frame had a full payload and was sent at maximum speed (minimum amount of idles, etc.) you could see about 206MB/s in theory of data payload on a 2Gb/s link.

RRR · Answer

2 gigabit per second devided by 10 makes 200 megabyte. But since 2 Gb is actually 2.125 Gb, it makes 212.5 megabytes per second.

As mentioned Fibre Channel "encapsulates" bytes with 2 extra bits, so each byte is 10 bits.

RRR · Answer

I've seen 201 once. I tuned ECC to report values over 150MBps to me with a thresshold of 2, so after 2 occurences I got an email that some port was doing 201MBps. Cool, hey ?

Summi1 · Answer

Thanks a lot for the answer...

RRR · Answer

Can you please mark the post as answered and hand out points for those who helped you ?
Next to each post you'll see buttons "helpful" and "correct". "Helpful" means 6 points and you can hand those out twice. The "Correct" means 10 points and you can only hand them out once.

RRR · Answer

I see you marked your question as answered. Can you reward any helpful or correct answers as such as well ?

Connectrix

Connectrix FC switches

Was this post helpful?