Hub or switch

I have just set-up a network with three PCs connected to an old server via a
hub.
The server has various external drives connected via firewire, USB2 and
firewire
800. We occasionally backup a lot of data from any of the PCs to any of the
external drives on the server.

The first time we tried to backup some data (200GB) onto the external drive
it
took well over 24 hours. My thinking is that the hub is not dual speed and
only
10baseT. Do I need to upgrade to a dual speed hub or are there other things
I
can try first, like perhaps changing some settings on the network PCI card
(duplex
mode?)? Would a switch be better for transferring this amount of data?

Many thanks in advance

Bart.

In article <bwT7d.59$(E-Mail Removed)>, "Mike" bigbart5
@hotmail.com says...
> I have just set-up a network with three PCs connected to an old server via a
> hub.
> The server has various external drives connected via firewire, USB2 and
> firewire
> 800. We occasionally backup a lot of data from any of the PCs to any of the
> external drives on the server.
>
> The first time we tried to backup some data (200GB) onto the external drive
> it
> took well over 24 hours. My thinking is that the hub is not dual speed and
> only
> 10baseT. Do I need to upgrade to a dual speed hub or are there other things
> I
> can try first, like perhaps changing some settings on the network PCI card
> (duplex
> mode?)? Would a switch be better for transferring this amount of data?
>
duplex is faster, but only works with a switch

Quick approximation:
100Mbps = 12.5Mbps
200000MB / 12.5MBps = 16000s = 4.5 hours

So if a 100Mbps network connection managed to transfer 100Mbits of data
in a second (which it doesn't), and there was nothing else using the
network, it would take 4.5 hours to copy the 200GB of data.

So upgrade your entire network to 100Mbps and a switch, and it will
still be on the slow side for shifting that amount of data. If you only
do it occasionally, and the network is otherwise adequate for your
needs, I'd suggest getting some hard drive caddies that allow you to
pull a disk from one of the machines and stick it in another to copy the
data across.

"Rob Morley" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) t...
> In article <bwT7d.59$(E-Mail Removed)>

> duplex is faster, but only works with a switch
>
> Quick approximation:
> 100Mbps = 12.5Mbps
> 200000MB / 12.5MBps = 16000s = 4.5 hours
>
> So if a 100Mbps network connection managed to transfer 100Mbits of data
> in a second (which it doesn't), and there was nothing else using the
> network, it would take 4.5 hours to copy the 200GB of data.
>
> So upgrade your entire network to 100Mbps and a switch, and it will
> still be on the slow side for shifting that amount of data. If you only
> do it occasionally, and the network is otherwise adequate for your
> needs, I'd suggest getting some hard drive caddies that allow you to
> pull a disk from one of the machines and stick it in another to copy the
> data across.

Thanks Rob.

We had all the drives plugged into various machines before, and we were
constantly plugging and unplugging bits of kit. So we've put the network to
centralise everything. We don't mind if shifting data takes a long time, as
long as we can leave it overnight and it's done by the morning.

What would you recommend for upgrading the network to 100Mbps in terms of
cabling and which switch would you recommend?

Thanks

Mike wrote:
> I have just set-up a network with three PCs connected to an old
> server via a hub.
> The server has various external drives connected via firewire, USB2
> and firewire
> 800. We occasionally backup a lot of data from any of the PCs to any
> of the external drives on the server.
>
> The first time we tried to backup some data (200GB) onto the external
> drive it
> took well over 24 hours. My thinking is that the hub is not dual
> speed and only
> 10baseT. Do I need to upgrade to a dual speed hub or are there other
> things I
> can try first, like perhaps changing some settings on the network PCI
> card (duplex
> mode?)? Would a switch be better for transferring this amount of
> data?
>
Sounds like you might have a duplex setting wrong on one of the machines.
If one is running at full when it should be half then your speeds will go
through the floor.
I'd still buy a switch though. A 4 port one shoudln't cost much more than a
tenner and will be far more effective than a hub.

--
Alex

"We are now up against live, hostile targets"

"So, if Little Red Riding Hood should show up with a bazooka and a bad
attitude, I expect you to chin the bitch! "

www.drzoidberg.co.uk
www.ebayfaq.co.uk

Rob Morley wrote:
> In article <bwT7d.59$(E-Mail Removed)>, "Mike" bigbart5
> @hotmail.com says...
> > I have just set-up a network with three PCs connected to an old server via a
> > hub.
> > The server has various external drives connected via firewire, USB2 and
> > firewire
> > 800. We occasionally backup a lot of data from any of the PCs to any of the
> > external drives on the server.
> >
> > The first time we tried to backup some data (200GB) onto the external drive
> > it
> > took well over 24 hours. My thinking is that the hub is not dual speed and
> > only
> > 10baseT. Do I need to upgrade to a dual speed hub or are there other things
> > I
> > can try first, like perhaps changing some settings on the network PCI card
> > (duplex
> > mode?)? Would a switch be better for transferring this amount of data?
> >
> duplex is faster, but only works with a switch

I don't think full-duplex will help much if you're transferring data in
one direction.

> 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.

> So if a 100Mbps network connection managed to transfer 100Mbits of data
> in a second (which it doesn't), and there was nothing else using the
> network, it would take 4.5 hours to copy the 200GB of data.
>
> So upgrade your entire network to 100Mbps and a switch, and it will
> still be on the slow side for shifting that amount of data. If you only
> do it occasionally, and the network is otherwise adequate for your
> needs, I'd suggest getting some hard drive caddies that allow you to
> pull a disk from one of the machines and stick it in another to copy the
> data across.

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.


From an Internet discussion (undated):
"Arno_Millenaar
Have tried about everything that I could find on the net, MTU, Rec/Send
buffer size adjustments, setting all network cards to full duplex
100Mps, etc, etc. Nothing really made a difference. Until I found
somewhere that somebody had changed it hub/switch and this solved the
problem. Could not really understand why as previous using w2k pc's the
problem was not there. However removed the 3-4 year old 3Com Hub's and
replaced it with a new 16 port EDIMAX. The main difference between the
3Com Switch (model 3C16750B) and the new EDIMAX (model ES-3116RL) is
that this new switch is an active switch with store-and-forward
switching architecture (512Kb memory buffer). With this new switch,
using a mix of about 10 PC's 1 x RH-Linux, 5 x w2k and 4 x XP (SP2) the
file transfer is back to where it belongs. Using the XP network monitor,
I can now see close 100% bandwidth utilization (with old 3Com switch
below 10% !) and no collisions. Before buying the new switch I tried
some other hub's I still had. However no improvement as they are all
'passive' switches.

I only paid for the EDIMAX switch EURO 69.=

Wanted to share this with this forum, as I have struggled so much in the
past weeks/months, and the solution to the problem wasn't obvious. So go
out and buy a new generation "Store and Forward" switching architecture
switch if you have similar problems."


HTH,
--
Michael Salem

In message <(E-Mail Removed)> , Rob Morley
<(E-Mail Removed)> writes


>>
>duplex is faster, but only works with a switch
>
>Quick approximation:
>100Mbps = 12.5Mbps
>200000MB / 12.5MBps = 16000s = 4.5 hours

So a 10Mb network would take a minimum of 45 hours. Therefore the
network must have 100Mb hardware end-to-end. The actual transfer rate
appears to be about a sixth of the theoretical speed. That suggests a
problem, I would have expected it to take around 8 hours.

I wonder what other network traffic was going on at the same time?

>
>So if a 100Mbps network connection managed to transfer 100Mbits of data
>in a second (which it doesn't), and there was nothing else using the
>network, it would take 4.5 hours to copy the 200GB of data.
>
>So upgrade your entire network to 100Mbps and a switch, and it will
>still be on the slow side for shifting that amount of data. If you only
>do it occasionally, and the network is otherwise adequate for your
>needs, I'd suggest getting some hard drive caddies that allow you to
>pull a disk from one of the machines and stick it in another to copy the
>data across.

Or got to gigabit Ethernet.


--
Bernard Peek
London, UK. DBA, Manager, Trainer & Author. Will work for money.

In article <VGU7d.234$(E-Mail Removed)>, "Mike" bigbart5
@hotmail.com says...
<snip>
>
> We had all the drives plugged into various machines before, and we were
> constantly plugging and unplugging bits of kit. So we've put the network to
> centralise everything. We don't mind if shifting data takes a long time, as
> long as we can leave it overnight and it's done by the morning.

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

In article <(E-Mail Removed)> , "Michael
Salem" a$-b$(E-Mail Removed) says...
> Rob Morley wrote:
<snip>
> > duplex is faster, but only works with a switch
>
> I don't think full-duplex will help much if you're transferring data in
> one direction.

True, but he was talking about changing duplex settings with his
existing 10Mbps non-switching hub.
>
> > 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.

I know - did you read the next sentence?
>
> > So if a 100Mbps network connection managed to transfer 100Mbits of data
> > in a second (which it doesn't), and there was nothing else using the
> > network, it would take 4.5 hours to copy the 200GB of data.
> >
> > So upgrade your entire network to 100Mbps and a switch, and it will
> > still be on the slow side for shifting that amount of data. If you only
> > do it occasionally, and the network is otherwise adequate for your
> > needs, I'd suggest getting some hard drive caddies that allow you to
> > pull a disk from one of the machines and stick it in another to copy the
> > data across.
>
> 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.

"Mike" <(E-Mail Removed)> wrote in message
news:bwT7d.59$(E-Mail Removed)...
>I have just set-up a network with three PCs connected to an old server via
>a
> hub.
> The server has various external drives connected via firewire, USB2 and
> firewire
> 800. We occasionally backup a lot of data from any of the PCs to any of
> the
> external drives on the server.
>
> The first time we tried to backup some data (200GB) onto the external
> drive
> it
> took well over 24 hours. My thinking is that the hub is not dual speed
> and
> only
> 10baseT. Do I need to upgrade to a dual speed hub or are there other
> things
> I
> can try first, like perhaps changing some settings on the network PCI card
> (duplex
> mode?)? Would a switch be better for transferring this amount of data?
>
> Many thanks in advance
>
> Bart.
>
>
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.

Dave

In article <(E-Mail Removed)>, "Bernard Peek" (E-Mail Removed)
says...
> In message <(E-Mail Removed)> , Rob Morley
> <(E-Mail Removed)> writes
> >duplex is faster, but only works with a switch
> >
> >Quick approximation:
> >100Mbps = 12.5Mbps
> >200000MB / 12.5MBps = 16000s = 4.5 hours
>
> So a 10Mb network would take a minimum of 45 hours. Therefore the
> network must have 100Mb hardware end-to-end. The actual transfer rate
> appears to be about a sixth of the theoretical speed. That suggests a
> problem, I would have expected it to take around 8 hours.

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.