2013-09-27 - Re: [GRASE-Hotspot] An idea for Grase hardware (Drazen)

Header Data

From: Drazen <dr***a@radez.hr>
Message Hash: 284ee80460dceb031e7b3491901cae474c3db82106cf17466ec24c5301e15e78
Message ID: <52455A28.5030603@radez.hr>
Reply To: <CAKDTiad=GZ2TkSgDjSE44VsR_LNx6Bbgw4J0Tr4hH8cnGHQ=Ww@mail.gmail.com>
UTC Datetime: 2013-09-27 03:12:56 UTC
Raw Date: Fri, 27 Sep 2013 12:12:56 +0200

Raw message 

On 27.9.2013 8:59, darnalis wrote:
> Wow drazen, you really read my mind.  I am also working on this on my 
> own but not yet being able to purchase a reliable usb lan ethernet 
> adapter.  Would love to hear more about the stability and the 
> performance of your setup. Thanks
>
> regards,
> darnalis
Hi darnails
To be honest, I didn't replace old-desktop grase for NB version yet. I 
don't have free time lately to finish all as planned. I plan to made 
power consumption measurements and comparison between desktop vs Nb. For 
that i need to prepare some simple hardware for 220V connections and 
measurement equipment. Nothing complicated but need my free time.
Much bigger DIY action planned is new housing for Nb-grase.

Anyway, my biggest concern on this construction is hard disk. Seem that 
those 2,5" devices laptop grade are not very reliable for 24/7 work.
At work I build two Atom miniITX machines with these disks. One is Grase 
server and other one is for other purpose. Last year disk died at one 
and just last week same at Grase.
Both machines where in miniITX housing. One Atom MB has CPU mini fan 
which dead first. Seems that produced higher temperature inside which I 
believe affect disc. Other one has passive CPU cooler and small fan at 
the housing. Can't say that overheating here was the cause. But founded 
dead.

I believe that if you are using "old" laptop which has SATA disk 
interface, using 3,5 disk old/new one instead is more reliable 
solution.  Unfortunately if very old laptop has EIDE there is no option 
here. Maybe some adapter EIDE to IDE or even SATA may solve.
In my case (on photos published) it is EIDE disk. Original disk went 
into unrecoverable lock (HP miracle invention!!) It is happened that I 
had disk from another very old laptop (Compaq) which I believe has 
slightly greater durabillity then disks we can buy today. Even so, I am 
planning to make backup of installation and prepare spare disk just in case.
Also I am thinking about more options here which need to be explored yet.

In any case, good cooling is always desirable.

Regarding ethernet-USB adapter, I did some google search to see what 
other people saying about. I found good reviews. Even found a guy who 
did speed/capacity measurements and comparison with standard ethernet 
adapters. His results where very good what courage me to choose that 
solution. Again, Mac adapter is recommended.

Speed or better say capacity, of any network adapter depends a lot of 
CPU speed and PCI bus capacity which is by the way always bottle neck at 
32bit systems. For simple WIFI networks 1 to 3 WiFi APs and not to many 
clients (up to 10 simultaneously connected and mail/browsing use) guess 
this will suffice.
For extensive use and  many clients connected, it is clear that overall 
server should be scaled up. But server speed also depends about services 
it has to run. Guess that the greatest CPU time consumer in Grase is 
Squid and its configuration. If Squid is configured to write down all 
traffic it is clear that it will consume much more CPU time and disk 
writtings then without this. Basically Grase's main job is traffic 
routing after authentication is done. Tim can say much more about all 
Grase services and how they scale regarding CPU/disk load.

This paragraf above express what most people logicaly think how things 
is going. However!

Overall speed may have several potential bootlenecks. Simple observation 
shows that on one side we have AP device which is typical 54Mbps .
capable at the WiFi side (as well as most clients). (Some Ubiquity 
devices can achieve 150Mbps 2,4GHzb and and 300Mbps 5GHz band). Real 
speed here is never that high. It greatly depends about radio 
signal/noise relation.
Each AP also has 100Mbps ethernet side which is overkill as we already 
know that WiFI side has 54Mbps theoretical maximum (never achieved). At 
other side most people has "broadband" ADSL Internet connection which 
scales from 2 to 24 Mbps (download direction only. Upload is 
significantly lower. A(DSL) states for asynchronous speeds up/dn).
As you can see, the biggest bootleneck is ADSL line itself. Even when it 
runs at ADSL2+ capable line with theoretical speeds 24/3,3 Mbps it is 
more then twice slower then 54Mbps.
 From this side of view, even low capable server will do the job. As 
seem it do.

Rgds
Drazen

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