[asterisk-users] Need input on scalable system design...

[Gareth Blades]

On 27/08/13 18:16, Gregory Malsack wrote:
>
> Hey All,
>
> Growing call center. Currently at about 200 call center staff, running 
> about 1000 calls per hour. Gearing up to double that. Not too sure 
> that a single server will support that growth. So, I'm trying to come 
> up with ways to scale the system and still maintain a simplistic 
> design. So I'd like to bounce some ideas around.
>
> Currently I am running on a Dell 1950, dual quad core 2.33ghz xeons, 
> with 16gb ram, and 2 tce400p cards. This server is managing the full 
> load of the company. We are recording all calls, running ivr, queues, 
> cdr, cel, and web for reporting. I currently have another 1950 of the 
> exact same specifications as a cold spare.
>
> Here's where you can see drawings of my current connectivity and an 
> optional connectivity I'm contemplating...
>
> *MailScanner has detected a possible fraud attempt from 
> "www.linkedin.com" claiming to be* 
> http://www.paydaysupportcenter.com/current.pdf 
> <http://www.linkedin.com/redirect?url=http%3A%2F%2Fwww%2Epaydaysupportcenter%2Ecom%2Fcurrent%2Epdf&urlhash=qLsB&_t=tracking_anet>*MailScanner 
> has detected a possible fraud attempt from "www.linkedin.com" claiming 
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>
> As you can see I currently have a separate sql server and a separate 
> storage server for the call recordings. This is all working fine.
>
> However, I'm thinking for scalability I should be looking to migrate 
> to a configuration similar to the one in option.pdf. Where I have a 
> VOIP gateway server that simply relays traffic and possibly can do 
> some load balancing or intellegent routing. But nothing more then 
> that, and possibly a second one of these online as a hot failover.
>
> Then have separate sql, storage, (i forgot it in the pic) web, and 
> asterisk servers behind that on separate dedicated network. Here's my 
> dilemma though, how do I balance the load across multiple machines for 
> scalability...
>
> Since 95% of our calls come into queues, I need to be able to maintain 
> queue stats and presence across all of the servers. Thus far, I've got 
> everything except the extensions.conf file into the mysql database. I 
> thought about setting up 2 servers, 1 for sales, and 1 for customer 
> service, then possibly break out each call queue to it's own server as 
> things grow. Just not sure if that's the right way to go.
>
> Then regarding extensions.conf, I've read that it too can be placed in 
> the sql database and accessed via switch. however it's resource 
> intense, so now I'm thinking of maybe putting that file on the nfs 
> server for all of the boxes to read from.
>
> As for the design of that file, I was kind of thinking of a modular 
> design within the file using various goto's and gosubs. Our business 
> model is based on affiliates and corporate marketing, so we have a ton 
> of did's that follow the same call flow with minor modifications in 
> some variables, as well as variations in call flow, and hours of 
> operation. Thus the modular design of the call flow. Then the primary 
> inbound context would simply be a list of did's pointing to a goto 
> with a list of the variations and variables for the did.
>
> Ok, now that I've melted your brains.... thoughts?
>
> Thanks all in advance for the discussion...
> Greg
>

We have a similar server but a single quad core at 3Ghz. It easily 
handles 400 concurrent calls with a lot shorter average call duration 
than you have. It doesnt do as much call recording but does do a lot of 
AGI stuff.

With regard to nfs thats fine for non real time stuff. Personally we 
have a test machine and multiple live machines and use subversion to 
commit any approved changes and then check them out on the live boxes. 
We dont need to worry about shared file space and we get version control 
of the configuration as an additional benefit.
Its similar for call recordings. We have call recordings going to a ram 
disc and then when they are complete there is a background process to 
copy them to the nfs volume. If nfs is unavailable then they are moved 
to the internal disk temporarily until the nfs is back online. We have 
never used this functionality but it add a little redundancy.

I would put opensips at the front end which looks at the incoming 
destination number and routes the call to the appropiate front end 
asterisk box depending on the queue it should go to. The other asterisk 
box(s) will be a backup so if one asterisk box fails then one of the 
others takes over running that queue automatically.

For call recording are you using mixmonitor?
I would consider using the normal monitor command and pass these 
recordings off to the nfs and have another machine process them by 
mixing both legs and perhaps converting to mp3 aswell.

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