Network Speeds - Help With my Maths

I have just shuffled my PC's around and have 1 main PC and 1 'server'
which is used to hold file backups.

I put W2K SP4 on the server but the network seemed slow so I've just
put XP SP2 on. It still seems slow to me but before I investigate can
somebody help with my maths to see if my expectations are correct?

I am using a Linksys router, a 3COM 10/100 NIC and an Intel PRO/1000
built in NIC. The network status on both PC's shows it is running at
100 Mbps.

If I have it right that's 100 mega-bits per second or 12.5 mega-bytes
per second.

On that basis I should be able to copy a 1GB file over the network in
about 82 seconds:

1GB = 1024MB
1024MB / 12.5 MBps = 81.92 seconds

Does that seem right or have I completely screwed up the maths?

I am getting an estimated time of 30/40 minutes in Explorer to copy a
1GB avi file from 1 PC to the other, on that basis it will take me
about 80 hours to back up a 160GB disk, that can't be right surely?

I have turned off the firewall on both PC's but it makes no difference.
I have just installed F-Prot anti virus, perhaps that's checking the
transfer bit by bit?

If somebody can confirm how long it should really take to copy a 1GB
file I will at least have a starting point :-)

--
Jeff Gaines
Posted with XanaNews 1.17.2.6

The problem isn't with your maths but with what you've ignored.

You've not included an allowance for network and protocol overhead.
Perhaps some here can tell you what to allow for this but about half
an hour for a 1 GB file seams about right from my experience.

On 14 Feb 2005 16:07:11 GMT, "Jeff Gaines"
<(E-Mail Removed)> wrote:

>
>I have just shuffled my PC's around and have 1 main PC and 1 'server'
>which is used to hold file backups.
>
>I put W2K SP4 on the server but the network seemed slow so I've just
>put XP SP2 on. It still seems slow to me but before I investigate can
>somebody help with my maths to see if my expectations are correct?
>
>I am using a Linksys router, a 3COM 10/100 NIC and an Intel PRO/1000
>built in NIC. The network status on both PC's shows it is running at
>100 Mbps.
>
>If I have it right that's 100 mega-bits per second or 12.5 mega-bytes
>per second.
>
>On that basis I should be able to copy a 1GB file over the network in
>about 82 seconds:
>
>1GB = 1024MB
>1024MB / 12.5 MBps = 81.92 seconds
>
>Does that seem right or have I completely screwed up the maths?
>
>I am getting an estimated time of 30/40 minutes in Explorer to copy a
>1GB avi file from 1 PC to the other, on that basis it will take me
>about 80 hours to back up a 160GB disk, that can't be right surely?
>
>I have turned off the firewall on both PC's but it makes no difference.
>I have just installed F-Prot anti virus, perhaps that's checking the
>transfer bit by bit?
>
>If somebody can confirm how long it should really take to copy a 1GB
>file I will at least have a starting point :-)

Robert Gauld wrote:
> The problem isn't with your maths but with what you've ignored.
>
> You've not included an allowance for network and protocol overhead.
> Perhaps some here can tell you what to allow for this but about half
> an hour for a 1 GB file seams about right from my experience.

Given the OP's decent hardware, I don't think so!

I've found that you should get about 60% of the theoretical throughput,
so about 8 megabytes/second.

I suggest the OP updates his NIC drivers and defrags his hard drives,
and then sees what he gets.

SiSoft SANDRA is a good program (just about the only one I know of) for
measuring throughput between 2 PCs.

However, I don't know how good routers are as a network switch, I use an
Intel InBusiness 10/100 megabit switch (Broadcom chipset).

HTH,
Anton

On 14 Feb 2005 16:07:11 GMT, "Jeff Gaines" <(E-Mail Removed)> wrote:

>
>I have just shuffled my PC's around and have 1 main PC and 1 'server'
>which is used to hold file backups.
>
>I put W2K SP4 on the server but the network seemed slow so I've just
>put XP SP2 on. It still seems slow to me but before I investigate can
>somebody help with my maths to see if my expectations are correct?
>
>I am using a Linksys router, a 3COM 10/100 NIC and an Intel PRO/1000
>built in NIC. The network status on both PC's shows it is running at
>100 Mbps.
>
>If I have it right that's 100 mega-bits per second or 12.5 mega-bytes
>per second.
>
>On that basis I should be able to copy a 1GB file over the network in
>about 82 seconds:
>
>1GB = 1024MB
>1024MB / 12.5 MBps = 81.92 seconds
>
>Does that seem right or have I completely screwed up the maths?
>
>I am getting an estimated time of 30/40 minutes in Explorer to copy a
>1GB avi file from 1 PC to the other, on that basis it will take me
>about 80 hours to back up a 160GB disk, that can't be right surely?
>
>I have turned off the firewall on both PC's but it makes no difference.
>I have just installed F-Prot anti virus, perhaps that's checking the
>transfer bit by bit?
>
>If somebody can confirm how long it should really take to copy a 1GB
>file I will at least have a starting point :-)

I haven't got a 1Gb file, so I just transferred 2x 615MByte ISO files and it
took 3:16 seconds.

the 1st file took 1:35 613MBytes
the 2nd took 1:41 615Mbytes

I also know from experience that the speed differs depending on which PC I
instigate the TX from

It averages about 6 - 6.5KBytes/second here (actual data transfere)

Clansman

On Mon, 14 Feb 2005 17:51:15 GMT, Clansman <(E-Mail Removed)> wrote:

>
>I haven't got a 1Gb file, so I just transferred 2x 615MByte ISO files and it
>took 3:16 seconds.
>
>the 1st file took 1:35 613MBytes
>the 2nd took 1:41 615Mbytes
>
>I also know from experience that the speed differs depending on which PC I
>instigate the TX from
>
>It averages about 6 - 6.5KBytes/second here (actual data transfere)
>
>Clansman
>
that should've read 6000 - 6500KBytes/second here.

Also it is a direct PC - PC connection @ 100Mbps

Clansman

"Jeff Gaines" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
[snip]
> I am using a Linksys router, a 3COM 10/100 NIC and an Intel PRO/1000
> built in NIC. The network status on both PC's shows it is running at
> 100 Mbps.
>
> If I have it right that's 100 mega-bits per second or 12.5 mega-bytes
> per second.
>
> On that basis I should be able to copy a 1GB file over the network in
> about 82 seconds:
>
> 1GB = 1024MB
> 1024MB / 12.5 MBps = 81.92 seconds
>
> Does that seem right or have I completely screwed up the maths?

The maths is basically right but ignores overhead. Windows file sharing
doesn't seem to saturate the network. IME the speed is 6-9MB/s (2-3 minutes
per GB). The theoretical maximum including TCP, IP and Ethernet overhead is
something like 11MB/s (1MB/s = 1048576 bytes/s).

Alex

On 14/02/2005 Alex Fraser wrote:

> "Jeff Gaines" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> [snip]
> > I am using a Linksys router, a 3COM 10/100 NIC and an Intel PRO/1000
> > built in NIC. The network status on both PC's shows it is running at
> > 100 Mbps.
> >
> > If I have it right that's 100 mega-bits per second or 12.5
> > mega-bytes per second.
> >
> > On that basis I should be able to copy a 1GB file over the network
> > in about 82 seconds:
> >
> > 1GB = 1024MB
> > 1024MB / 12.5 MBps = 81.92 seconds
> >
> > Does that seem right or have I completely screwed up the maths?
>
> The maths is basically right but ignores overhead. Windows file
> sharing doesn't seem to saturate the network. IME the speed is
> 6-9MB/s (2-3 minutes per GB). The theoretical maximum including TCP,
> IP and Ethernet overhead is something like 11MB/s (1MB/s = 1048576
> bytes/s).
>
> Alex


Thanks to everybody for their input :-)

I found a 639MB iso, not too different from the one Clansman used and
that one file is taking between 75 and 145 seconds to copy, as Clansman
said depending on which PC initiates the transfer.

It seems to confirm I have a real problem here :-(

I have even swapped routers and, after re-booting, get the same
results. I'll concentrate on running AdAware, SpyBot etc. tonight and
start afresh tomorrow.

Thanks again guys, at least I know I've got a problem, just need to fix
it now :-)

--
Jeff Gaines
Posted with XanaNews 1.17.2.6

On 14 Feb 2005 16:07:11 GMT, "Jeff Gaines" <(E-Mail Removed)>
wrote in <(E-Mail Removed)>:

>I have turned off the firewall on both PC's but it makes no difference.
>I have just installed F-Prot anti virus, perhaps that's checking the
>transfer bit by bit?

I have seen very poor performance when copying a lot of small-medium
sized files due to anti-virus being on (at both ends!). Switching off
the real time mode AV at both ends made a huge difference. How much this
would affect the transer of a large file may depend on which AV you are
using, but it would be worth investigating (with suitable precautions of
course).

--
Owen Rees
[one of] my preferred email address[es] and more stuff can be
found at <http://www.users.waitrose.com/~owenrees/index.html>

On Mon, 14 Feb 2005 17:31:15 +0000, Anton Gÿsen
<(E-Mail Removed)> wrote:

>Robert Gauld wrote:
>> The problem isn't with your maths but with what you've ignored.
>>
>> You've not included an allowance for network and protocol overhead.
>> Perhaps some here can tell you what to allow for this but about half
>> an hour for a 1 GB file seams about right from my experience.
>
>Given the OP's decent hardware, I don't think so!
>
>I've found that you should get about 60% of the theoretical throughput,
>so about 8 megabytes/second.
>
>I suggest the OP updates his NIC drivers and defrags his hard drives,
>and then sees what he gets.
>
>SiSoft SANDRA is a good program (just about the only one I know of) for
>measuring throughput between 2 PCs.
>
>However, I don't know how good routers are as a network switch, I use an
>Intel InBusiness 10/100 megabit switch (Broadcom chipset).
>
>HTH,
>Anton

Well here's a thread to watch so I can find how to improve my speed
then.

Robert Gauld wrote:

> Well here's a thread to watch so I can find how to improve my speed
> then.

How about stop using shitty Realtek/SiS/whatever NICs you use? That's
about the only reason I can think of for you getting shit transfer
speeds. But, if you're happy with having to wait half an hour to
transfer a gigabyte, then I haven't got a problem with it.