Re: Backup to USB works but to NAS fails

Speed is 'autonegotiated' with the hub/switch (usually)
Some earlier hubs/switches had little dip-switches to set the connection.
On windows it's a setting in the network card settings and usually
worth setting to what it should be (rather than autonegotiate.)
On a HUB ALL data is transmitted to ALL ports.
This used to be a HUGE concern with broadcats network protocols
sucs as NetBEUI, however this -still- has an impact..add the PC's on
the hub must clearly recieve the data packet. fortunately most modern
network
cards are 'paralel tasking' and perform the MAC inspection at the card.
(is the packet for me??) however some 'cheap' cards have moved this back
into
the CPU.. this then means:
if you have a 10mb client ALL data must slow down to that speed.
This is very painfull for a 100mb node sending to a 100mb client as the
slow down is achieved by using data collisions to force the sending system
to back off.
Data throughput on the lan *can* be a factor of the cpu/bus/memory
performance on all the connected pc's, even tho they are not in the
conversation.
This used to be the BIG factor in LANMAN/WfWg/NT3.51/NT4 networks
that used the monolithic NetBEUI protocol stack.
no I hope I can remember the figures correct...
I setup a demo rig once with two NT4/SCSI/P200 machines and a dog slow
WfWg/MFM/386sx25 on a 10Base2 (thin-wire) lan [same sort of effect as
10/100mb hub with 10mb clients] copying 120MB file between the two big
systems took about 8 mins average over several hundred samples (left a batch
job going overnight) then turned on the WfWg pc..despite it not touching or
talking to the other 2 systems the time went up to 40mins for the same
120mb file!!! Yeah.. 15MBytes/min throughput vs 3MByte/min..
that gives me:
15MBytes * 10 = 150Mbits/min (8bit data + start & stop bit = 10 bits for 1
Byte)
150Mbits/min /60 = 2.5Mbits/sec.. hey 25% throughput.... was good in those
days
wheras
3MBytes * 10 = 30Mbits/min (8bit data + start & stop bit = 10 bits for 1
Byte)
30Mbits/min /60 = 0.5Mbits/sec.. Lots slower...
Now I'm not saying things will be that slow but allowing for modern hardware
to improve the throughput to 50% (don't forget the other systems on the lan
will slow things down) you will achieve 30MBytes/min that's 22 hours for
your
backup..
40GB * 1024 = 40960MB / 30MB/m = 1365mins /60 = 22.7 hours

Getting this up to 100Mb/s lan speed (either back-to-back or upgrade to
switch)
will improve things..
say we only get 10% throughput, that is 60MBytes/min = 11 hrs
if we get 20% throughput, thats 120MBytes/min = 5.5 hrs

Re the switches..
Which ones were you looking at?
One switch is not the same as the next..
The key two factors that 'rate' a switch are:
-a- the Forwarding rate
-b- the backplane throughput.
My base rule is if the manufacturer doesn't quote the figure, it's not very
good.
However I've used the Netgear FS-516 units and they are fairly good.
They show a good throughput and lan improvement over their FS1x and GS1x
range (the FS1x and GS1x ranges have a shared backplane, which is not much
better than using a hub.. ok well its better than a hub, but still poor
throughput)
Most cheap unbranded and entry-level units are of the ilk of the FS1x range.
FS516 specs
(http://www.netgear.com/Products/Switches/UnmanagedSwitches/JFS516.aspx?detail=Specifications)
I've seen the FS516 for $80ish..
(http://reviews.pricegrabber.com/switches/m/41448/)
Personally I'd pick up a second hand HP Procurve 2424m off Ebay..

In the short term a $15 gig network card in the server and x-over cable into
the NAS
box is the quickest fix. Make sure you set the server IP to different subnet
and to
fixed IP, also turn off autonegotiate on the LAN card and fix it to 1000
duplex.
But then, as I said above, just getting the server running at 100Mb/s could
bring
your backup time down to 5.5 hours!!!!


You should also try fixing the speed on the lan card on the server, try
100MB simplex
(duplex is for switches and direct x-over).


Do some throughput tests with a mid-sized file.
Use xcopy at the command prompt and drag-drop in the GUI is unpredictable

REM ********** batch start
Net use x \\nas\share
time /t
xcopy my-local-file x:\*.* /Y
time /t
xcopy my-local-file x:\*.* /Y
time /t
xcopy my-local-file x:\*.* /Y
time /t
xcopy my-local-file x:\*.* /Y
time /t
xcopy my-local-file x:\*.* /Y
time /t
net use x /d
pause
REM ********** batch end

save the above as a batch file changing the relavent bits..
Use a small enough file for the test to complete inside 15 mins or so
Work out what your average thoughput is..
Change something.. see what the new throughput is.
Just a thought.. there probably are some tools out there that can
test throughput for you.. worth a google..


It's always worth while knowing what the throughputs are for various
machines on the lan.
sort of the base 'know your network'.. so when you decide to move 180GB from
one machine to another, you know roughly how long it will take..
Also you have a baseline to test against when diagnosing issues in the
future.


David Barnes


"Another Brian" <notbrian@xxxxxxxxxxxxxxx> wrote in message
news:%23O%23pQNICIHA.464@xxxxxxxxxxxxxxxxxxxxxxx
OOPS. One other discovery. I may have found the source of the problem. In
my original post I asked how to learn the speed of my network. I never
thought of going to Task Manager and looking at the Networking tab. Low
and behold it says that the WAN connection is 100 Mbps. and, ARGH, the LAN
is running at 10 Mbps.

Is the LAN speed controlled by the NIC in the server or by the first
object, the hub, that connects to the NIC? When I looked at the NIC last
night, I thought that it said that it was 10/100 Mbps, but I'll have to
look again in the morning.

Brian Bygland

"Another Brian" <notbrian@xxxxxxxxxxxxxxx> wrote in message
news:egTYE2HCIHA.484@xxxxxxxxxxxxxxxxxxxxxxx
Hi David. Here's where we stand ...

I've moved the NAS so that it hangs directly off the hub (yes it is a
hub, not a switch) so it is SBS > hub > NAS. The backup started at 10:30
PM PDT last night and is still running as 5:47 PM PDT today, or in other
words, it's been running for almost 19 hours. Not good. Judging by the
size of the resulting backup file, it should be almost complete.

Changing the hub to a switch might make a bit of difference, but I don't
think that much. An 8-port switch runs around $60, but I'm currently
using all 8-ports of the hub and could really use 3 more ports, so I
might as well go for a 16 or 24-port switch which start at $120.

Activating the second 100Mb NIC in the server and hanging the NAS
directly off it (I guess I'd need a crossover cable to do that) might
also help, but I doubt that it would reduce the backup from 19 hours back
down to the 5 hours when I backup to the attached USB drive.

That leaves putting in a GIG NIC in the server and hood the NAS directly
to that. I can get a GIG NIC for under $30 and I understand that I can
use CAT5e cable instead of the more expensive CAT6.

Any other ideas?
Brian

"David Barnes" <david at bitsolve dot com .nospam.ignore.net> wrote in
message news:%237gJ$3BCIHA.4176@xxxxxxxxxxxxxxxxxxxxxxx
Brian,
How's it panning out?
David

"Another Brian" <notbrian@xxxxxxxxxxxxxxx> wrote in message
news:O%23vU4z3BIHA.1408@xxxxxxxxxxxxxxxxxxxxxxx
It's a small white box with 8-ports located on its end behind a bunch
of books with not enough slack wire to move it far enough to read any
of its labels. Having just read the difference between a switch and a
hub and realize that a switch is better. I'm heading up on-site in a
few minutes and will take a look even if I have to unplug everything to
see what it is (everyone should be out to lunch). If it is a hub, which
I suspect, after lunch maybe I'll head over to Fry's and get a switch
with more ports.

Brian Bygland









.

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