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Network and disk throughput

Got problems with your B2 or B3? Share and get helped!
Puma
Posts: 230
Joined: 29 Sep 2008, 06:30

Re: Network and disk throughput

Post by Puma »

Hello,

Turning of functions cannot be the cause.
I have only Mail and sometimes ftp turned on.

Gigabit switch and CAT5 cables and 6mb/sec speed.

Puma
Linux is like a wigwam - no windows, no gates, apache inside!
mad
Posts: 43
Joined: 11 Oct 2008, 14:48

Re: Network and disk throughput

Post by mad »

Assuming that asparak reports his numbers in Mb and Puma in MB the difference is not all that big.

59Mb ~ 7.4MB for asparak
48Mb ~ 6MB for Puma

Still a difference but it could well be down to cables/drives/whatever.
Filius
Posts: 14
Joined: 26 Oct 2009, 02:21

Re: Network and disk throughput

Post by Filius »

*facepalm*

Wish people would stop enforcing this silly Mb/MB notation and just specify mbit or mbyte. I of course assumed aspark to get 50+ mbyte. Not mbit.

Seems we are all suffering from this performance then. I quite agree with anbn that marketing the gbit ascpet of the B2 is missleading when it cannot even sustain 100mbit transfer rates.

My problems are not caused by the cable. I have been troubleshooting this for half a year. Varios cables have been involved, none of which made any difference either way on the speed.

Wery disapointed. I will not be recommending B2 anymore.
Puma
Posts: 230
Joined: 29 Sep 2008, 06:30

Re: Network and disk throughput

Post by Puma »

Filius,

Why so disapointed?

If you buy a NAS for example a ReadyNAS from netgear or a QNAP the performance will be better but not that better.
With a Gbit network and good cables you then will get 10 - 12 MB/s.
And people find that comfortable in reviews.

Now you get a linux box with lots of options with 6-7 MB/s and bompletely adjustable.

I have bubba TWO run as proxy server / Mail server / Internet filter for the kids / Raid 1 / auto backups / torrent this cannot be done with a normal NAS.

Of course I would like it to be a bit faster but as stated earlier I'm happy.

Puma.
Linux is like a wigwam - no windows, no gates, apache inside!
asparak
Posts: 173
Joined: 08 Jun 2009, 07:38

Re: Network and disk throughput

Post by asparak »

Network speeds are measured in Mb or Mbits
data capacity is measured in MB or MBytes.

Its industry standard notation and has been for a very very long time.
I'm currently looking at the kernel /proc ipv4 and tcp options for sysctl -p to see if I can spot why this is worse than it should be and maybe tweak things a little.
Excito, feel free to chip in here. I for one would trade off a little extra heat for a better performance, even if it was just to 100Mb/s
zander
Posts: 141
Joined: 01 Jan 2009, 23:16
Location: las vegas, nv, usa
Contact:

Re: Network and disk throughput

Post by zander »

the transfer rates posted by excito for the bubba are in units of bits not bytes. and usually those rates are distributed across some number of channels (i think its eight channels). if you read the definitions of these things such as Gb eithernet on wikipedia you can get the details.

with the info on those links lets pare this down...

so if the bubba has a stated transfer rate of 1Gb that is (1Gbit/s)*(byte/8bits)*(1000M/G) =125Mbyte/s.

if that is distributed 8 channels per cat6 port (125Mbyte/s)/(8channel)=15.625Mbyte/s*channel).

this number is farther distributed into transmit and receive channels thus observe...

((15.625Mbyte/s)*channel)*(txrx/2channel)= 7.8125Mbyte*txrx/s.

7.8125Mbyte*txrx/s is roughly what has been reported. perhaps with asparak using cat6 and Puma using cat5 cables. there are good reasons that the actual data transfer rates should not overwhelm the theoretical standards. for example how would you handle errors if you exhausted your capacity to transmit and receive data?

i reject the idea that excito is misleading anyone.
~alonzo...
mad
Posts: 43
Joined: 11 Oct 2008, 14:48

Re: Network and disk throughput

Post by mad »

Care to explain where you get your numbers from? Especially the channel stuff.
zander
Posts: 141
Joined: 01 Jan 2009, 23:16
Location: las vegas, nv, usa
Contact:

Re: Network and disk throughput

Post by zander »

http://en.wikipedia.org/wiki/Fast_Ethernet#100BASE-TX


the first 8 chanels are physical.

the second two groups of calculations are logical and carried in the wires.

observe the units check.


the most authoritative place for you guys to get info on this is http://standards.ieee.org/
~alonzo...
Henri
Posts: 62
Joined: 14 Jul 2009, 07:56

Re: Network and disk throughput

Post by Henri »

Quickly read through your link and cannot agree your information about Gigabit Ethernet maximun speed being ~7,8 Mbyte/s. 8 Channnels ???

125 Mbytes/s as theoretical maximum transfer rate seems right.
I don't buy that 7,8 Mbyte/s max transfer rate for a gigabit Ethernet, because I can get my 100Mb Ethernet to transfer over 6 Mbyte/s even with older PC hardware.
mad
Posts: 43
Joined: 11 Oct 2008, 14:48

Re: Network and disk throughput

Post by mad »

zander wrote:http://en.wikipedia.org/wiki/Fast_Ethernet#100BASE-TX


the first 8 chanels are physical.

the second two groups of calculations are logical and carried in the wires.

observe the units check.


the most authoritative place for you guys to get info on this is http://standards.ieee.org/
What you've done is calculated the theoretical maximum transfer rate for ONE wire in a cat5/6 cable? How does this relate to the performance of the Bubba?
asparak
Posts: 173
Joined: 08 Jun 2009, 07:38

Re: Network and disk throughput

Post by asparak »

Let's not get into a technical discussion about standards, or we can start talking about 2 pairs for 100Base-TX and all 4 pairs for 1000BaseT using the same 125MBaud as 100Base-X, but with a level 5 noise immunity achieving the same as the 3 level on 100Base-X, but with a 4 dimensional trellis Coded modulation achieving 6dB across all 4 pairs at up to 250Mhz on cat-6, as opposed to up to 100Mhz on Cat 5 and 5e. We can start talking about which rev of 802.3 they are using etc, which is all fairly irrelevant.

Let's just agree, we would like some kind of clarification statement from Excito on network throughput, because on the face of things, the results we are seeing don't appear to gel with the specification of the devices.

I'm still looking at the kernel, proc and ipv4 setups etc, but so far I haven't seen anything untoward in the way they are configuring the system.
asparak
Posts: 173
Joined: 08 Jun 2009, 07:38

Re: Network and disk throughput

Post by asparak »

Hi Guys,

Ok: here is the definitive answer. I have spoken to Excito at length and confirmed their answer with my own testing. Network throughput is limited by the speed of the CPU in the current Bubba2. With my Bubba 'maxxing' out at just over 7MB/s throughput, CPU utilisation is 100%, so it simply cannot process the data stream any faster. They are aware of this and options are being looked at for a future version of the Bubba product line.

First thought that crossed my mind was offloading the network handling to a smart network port or secondary CPU, but that is probably not technically possible in a low cost/low power device.

I have to say (personally) though: 99% of the time 7MB/s is perfectly adequate for a house full of gamers playing MMORPG's online and surfing at the same time. It is only when I need to transfer large amounts of data at the same time, such as a 150GB backup that this becomes an issue.

Rik
Henri
Posts: 62
Joined: 14 Jul 2009, 07:56

Re: Network and disk throughput

Post by Henri »

Hi

Just a bit curiousity.

Asparak are use using Jumbo frames for that 7MB maximum data rate or is that achieved with standard sized Ethernet frames ?
endecotp
Posts: 2
Joined: 12 Apr 2007, 10:40

Re: Network and disk throughput

Post by endecotp »

Hi Filius,

6 MBytes/second looks about right to me. I have an NSLU2 that serves a bunch of USB flash drives over NFS, and I get about 3 MB/s to/from it. The Bubbla has a similar architecture but more RAM and faster disks, so 6 MB/s sounds about right. For higher performance than that you need something with a more hefty processor, e.g. some of the ~ 1 GHz Marvell chips (e.g. these QNAP devices: http://www.cyrius.com/debian/kirkwood/qnap/ ) or an Intel Atom (QNAP and Synology have some).

There are some good comparison tables at smallnetbuilder:
http://www.smallnetbuilder.com/componen ... Itemid,190

I believe the comments about cable quality are bogus.

Regards, Phil.
asparak
Posts: 173
Joined: 08 Jun 2009, 07:38

Re: Network and disk throughput

Post by asparak »

I wouldn't say cable quality is bogus; good quality cables whether Cat 5 or Cat 6 are going to be better than cheap or poorly made ones and STP will be less prone to outside influence than UTP, but in this case, they are not the limiting factor. It was definitely worth spending the 3GBP to replace the last Cat 5e patch cable in my network with a CAT 6 STP one to validate though.

I do have Jumbo frames enabled, because all my kit and cables are able to properly support it but throughput is not dramatically different without it switched on.

I'm continuing to work with Excito, to see if I can tweak performance in other ways, until the next generation of Bubba comes along. I like HTML inline in my Horde setup for instance and that was trivial to do.

Problem with a (relatively) hefty CPU like a Marvell or Atom is they dramatically increase the power consumption of a device which is designed to be low power, so Excito may not choose to go that route. Who knows what the next generation system will hold? I'm sure we will find out in due course, but if you have wish list items for a future system, tell them now so they can evaluate options.
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