I believe DAC stands for direct attach copper (not cable). They are thick and can be unwieldy but can be cheaper for really short runs (like a patch cable distance).
Fiber is really light and thin but you have to be careful about bending it because it can fracture internally.
Thanks for that
Finally getting back to you guys with the iperf results. Pleased to see I can just about hit the 10 gigabit.
However, I have definitely taken away the message that if I really want a “true” 10g NAS, I will need a more powerful processor (and probably RAIDed SSDs or some sort of write buffer/cache).
This might help your CPU bottleneck:
oh wow, yeah looks like there is more I could definitely do in future.
I know you already have SFP+, but I wanted to point out that 10GBASE-T exists.
This is the cheapest, most accessible, way a consumer can get 10Gb speeds. The reviews on the NIC are pretty good, but the switch seems iffy.
These use RJ-45, so no changes to a cable are necessary as long as they support 10Gb over the distance required. Cat 6 cables support 10GBASE-T over 55 Meters for example. Cat 5 does not. Cat 6e does for 100 Meters.
I agree that for a lot of consumers, this may be the solution, but personally I found that a direct host-to-host SFP+ connection was the cheapest/easiest for me, with a pair of those cards second hand being like £35 on ebay, and the cable being around £15. It definitely costs less than that switch or that single NIC. Obviously if you want new from a site like Amazon then maybe 10GBASE-T is the best solution.
Pretty sure that CPU is going to hate life, havent really seen any good sites that have how much cpu you need for 10gb. My lowest is a 4130t and i maxed out my disks, never ran jperf/iperf due to there being no need as 8x3tb WD red in RZ2 couldnt saturate the link anyway.
You’re certainly right that to make full use of the 10g connection, you need a fast processor (like a Ryzen 7) and be able to write to a fast storage area, such as a 960 EVO or SSDs in RAID 0.
However, having the 10g connection is still useful as getting 3 or 4 gigabit out of it is still a lot faster than using the normal gigabit connecion.
It is easier to set up, but the NIC’s are much more expensive. I’ve purchased used SFP+ cards for $15. Transceivers and OM3 fiber are cheap now too.
With the exception of gigabit switches with 2-4 10Gb ports, I think the cheapest 10Gb switch is the Ubiquiti ES-16-XG which accommodates both SFP+ and 10GBASE-T.
Cat6a
https://www.bicsi.org/double.aspx?l=3382
Can Category 6 Run 10G in Distances Less than 30 Meters?
In 2006, class E/category 6 (screened and unscreened) and class F/category 7 (screened) cabling standards existed as referenced in Table 55-12 (below). When IEEE 802.3an-2006 published, the class Ea/category 6a and class Fa/category 7a cabling standards had not yet published. Both have since published.
IEEE 802.3an-2006, Table 55-12, Cabling Types and Distances
Cabling
Supported link segment distancesClass E / Category 6 - 55 m to 100 m*
ISO/IEC TR-24750 / TIA/EIA TSB-155
Class E / Category 6: unscreened - 55 m
ISO/IEC TR-24750 / TIA/EIA TSB-155
Class E / Category 6: screened - 100 m
ISO/IEC TR-24750 / TIA/EIA TSB-155
Class EA / Category 6A - 100 m
ISO/IEC 11801 Ed 2.1 / TIA/EIA-568-B.2-10
55 meters is enough for most consumers.
That is true, but:
https://arstechnica.com/civis/viewtopic.php?t=1167469
EDIT
Basically, the Cat6 standard says 10Gb, but the 10GBASE-T standard says Cat6a. A high quality Cat6 cable will probably work for short distances but you might run into issues.
You can do 10GBase-T over cat5e up to 45m, if you already have cat5e and it’s not a super long run, and it’s nicely terminated at ends, it might just work.
10G (let alone 40G that you can do today with a pair of QSFP+ cards and some dac/aoc/fiber) is still very much a niche.
One day, it’ll be on all motherboards, and there will be WiFi routers with 10G those ports and 8 port switches will cost less than $100, but we’re not there yet.
Maybe just better software, can you dd into/from a file locally at 1GB/s or faster, have you tried bringing up a simple ftp server?
You’re right about better software. iPerf was able to show that I can get the 10 gig. Perhaps FTP would require less CPU work than rcp, but the issue has now been resolved and I got a tutorial out of it so thank you all.
Dont forget that most applications for file transfers are single threaded…which will part of the challenge when trying to saturate a link.
Try moving several files at once… also.
I wrote a simple webserver in go that streams data from a random buffer in http response and a few lines of JavaScript that can run in a browser and displays how much data was downloaded over time, basically a speed test.
It had no issues downloading data at much higher rates than 10Gbps over a single http connection.
My point is, it’s not the single-threaded-ness that’s the problem, it’s just some apps are bad and inefficient, and some are just old and when they were written how well they’d perform on networks as fast as today’s networks was not a concern.
This is very true.
Going forward software will likely be better and working across multiple threads. Times r a changin’ for the better with Ryzen and new languages like Go, and Rust making multi-threading (or at least parallel processing) more common (even though I’ve been doing this in Java for years).