Hub or switch

"Michael Salem" <a$-b$(E-Mail Removed)> wrote in message
news:(E-Mail Removed) T...
> Rob Morley wrote:
> > Quick approximation:
> > 100Mbps = 12.5Mbps
> > 200000MB / 12.5MBps = 16000s = 4.5 hours
>
> This is seriously over-optimistic; a 100Mbps network will not come close
> to this speed. I'd expect about 4 Megabytes/sec.

With modern machines and the right software, it's not hard to get well over
10MB/s useful data transfer over a 100Mb/s network. The theoretical maximum
(assuming full duplex) for TCP segment data is around 11MB/s, IIRC. But in
practical terms, Rob is closer on the basis of my experience; 4MB/s is very
pessimistic, double that is not unusual for Windows' file sharing. I get
7.5MB/s from a crusty old K6-2, albeit at about 70% CPU usage.

Alex

Me:

> > This is seriously over-optimistic; a 100Mbps network will not come close
> > to this speed. I'd expect about 4 Megabytes/sec.

Rob Morley:

> I know - did you read the next sentence?

Yes, but it is very useful to have an idea of the speed one can actually
expect - 3 times slower than nominal.

> > > So if a 100Mbps network connection managed to transfer 100Mbits of data
> > > in a second (which it doesn't),

> > For the specific purpose of transferring large amounts of data, you
> > might experiment with a simple point-to-point connection using 100Mbps
> > network cards in both machines and a Cat5 crossover cable without a hub
> > or switch: this will give you a benchmark to aim at with your switch.
> >
> This should make next to no difference on a quiet network.

It will rule out problems due to the gear used. In my posting I quoted a
message from somebody who claimed to have radically improved his
throughput by changing from one piece of 100Mbps gear to another. If and
only if you do this and your speed increases dramatically, you need to
do something about your switch/hub.

With a crossover cable you can play with the various parameters of the
NICs you are using.

HTH,
--
Michael Salem

"Rob Morley" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) t...
> I assumed that they'd given up copying the files after a day, and never
> finished. I also assumed that the hub was 10Mbps, but on second reading
> it appears that it might be 100Mbps but running badly.

We started the data transfer on Friday late afternoon and it was finished on
Sunday. About 48 hours or so. There was no other traffic.

Having checked on the manufacturers website the hub appears to be a 10Mbps.

Thanks.

"logized" <no-(E-Mail Removed)> wrote in message
news:cjpd7k$m8b$(E-Mail Removed)...
> An online file transfer calculator could give a rough idea of how long it
> should take to transfer a single file size, see
> http://www2.arnes.si/~kriskem1/hihi/calc_trans.htm
> If you are transferring many files and directories, then the server would
> also add to the delay as it works hard to create the new files and
> directories.
> If your hub is only 10Mbs, then it is worth upgrading anyway as 100Mbs
> switches can be bought quite cheaply and also upgrade the pc network
> adapter cards if not already compatible.
> Enabling full duplex could improve the transfer time slightly as it would
> enable the server to send acknowledgements without interrupting the
> transfer.
> Using a backup program that optimises the compression of files during
> transfer could save time also.

Thanks Dave. All the data is already as compressed as it can be.

"Rob Morley" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) t...
> Fairy nuff. Gigabit on copper is getting cheaper these days:
>
> http://www.ebuyer.com/customer/produ...duct_uid=51797
> http://www.ebuyer.com/customer/produ...duct_uid=58040
>
> >
> > What would you recommend for upgrading the network to 100Mbps in terms
> > of cabling and which switch would you recommend?
> >
> You don't say what the physical layout is, so for cable I can only say
> Cat5e. I tend to use D-Link kit because it's cheap (some would say
> "cheap and nasty", but I've never had any problems). Netgear and
> Linksys do similar stuff.
>
> http://www.ebuyer.com/customer/produ...duct_uid=26037

Yeah, it's Cat5e.

Thanks for the suggestions.

In article <Lyg8d.128$(E-Mail Removed)>, "Mike" bigbart5
@hotmail.com says...
>
> "Rob Morley" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) t...
> > I assumed that they'd given up copying the files after a day, and never
> > finished. I also assumed that the hub was 10Mbps, but on second reading
> > it appears that it might be 100Mbps but running badly.
>
> We started the data transfer on Friday late afternoon and it was finished on
> Sunday. About 48 hours or so. There was no other traffic.
>
> Having checked on the manufacturers website the hub appears to be a 10Mbps.
>
It's working OK then - 200GB in 48 hours is better than 9Mbps.