[Asterisk-Users] Can this config sustain 30 users?

[Erick Perez]

Well thanks all for your responses. My original intention was to
address the mistic know-how about machine calculations, and I still
feel the shadows remain.

Why? Because to achieve a 24 user PBX-only/One E1, I was going to
install a Dual Xeon with 2 GB of RAM and a 3ware card runing RAID-1
with two sata3 disks.
Now This thread tells me that my dual core pentium d (a 700$ computer)
will do the work. (the other equipment costs about 3500.00$). I do
realize that i must minimize transcoding (ulaw all the way) but you're
telling me it will work for 24 users (let's say 30 for round numbers)
all with SIP phones in an IP network.

Below are some comments that i found googling and doing some
calculations myself. I do not enforce or deny any of them, please feel
free to tell me if Im wrong.

(not confirmed)a- A voice channel takes 30mhz (60mhz in duplex mode).
So A 2.66 Ghz CPU can sustain about 43 calls (2600mhz/60mhz=43calls),
not taking into account other factors that may increase/decrease the
number of calls at the same time.

b- 24 users talking ulaw (-+ 80kbps per channel) consume 1920kbps and
in full duplex they consume 3840kbps (about 3.75 megabits/s).

c- To Calculate the bandwidth DDR memory can achieve (example PC4200)
,to get the transfer rate, multiply the width of the module (8 Bytes)
by the rated speed of the memory module (in MHz): (8 Bytes) x (533
MHz/second) = 4,264 Mbytes/second or 4.2 Gbytes/second (34gigabits/s),
hence the name PC4200

So, will all of this in mind,
CPU Dual Core 533FSB, 2.66 Ghz speed
DDR533mhz, One gigabyte. (2x512)
Two Sata disks (each sata pumps 1.5 gigabits/s)
Motherboard Intel 945 at 533FSB

Means that the cpu,the ram and the board can achieve (see point b)
about 34 gigabits of data transfer, but 24 users only generate 3.75
megabits. So this is more than covered.
However if we take into account the lowest performing component on
this system (the sata disks) we go down to 1.5gbits/s which still
seems to be enough.

Please please correct me if im wrong (or crazy)

Thanks,


References:
http://en.wikipedia.org/wiki/Front_side_bus (bus bandwidth table)
http://www.acme.com/build_a_pc/bandwidth.html
http://www.lostcircuits.com/memory/ddrii/
http://bvio.ngic.re.kr/Bvio/index.php?title=Front_side_bus


On 6/13/06, Mike Fedyk <mfedyk at mikefedyk.com> wrote:
> Erick Perez wrote:
> > I just don't want to install it and then after a 5th user going to
> > call someone the asterisk begin to crash due to lack of resuources.
> Check the wiki for SIP load generation tools you can use to test your
> setup on any number of calls you like.
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-- 
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Erick Perez
Panama Sistemas
Integradores de Telefonia IP y Soluciones Para Centros de Datos
Panama, Republica de Panama
Cel Panama. +(507) 6694-4780
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