Re: Backup to USB works but to NAS fails

Thank you, David. You are a wealth of knowledge. I'll work through
this and play with my network over the next week or so.

Brian Bygland

"David Barnes" <david at bitsolve dot com .nospam.ignore.net> wrote in
message news:OuQ8gsNCIHA.1208@xxxxxxxxxxxxxxxxxxxxxxx
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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