What are the main reasons behind 25 Agents per Dialer ratio

[bryan.kewl]

Hi

I am interested in knowing the primary reasons behind 25 agents per dialer ratio. What are the factors that makes it difficult to handle lots of agents on 1 dialer.

[boybawang]

* vicidial uses the meetme module of asterisk which is a resource hog
* 25 per server is the standard for outbound, if your purely inbound you can do 50 to 60 agents depending on how its configured, I have done 30 agents max stable on a server running outbound campaigns with finetuning on mysql apache and using ulaw and alaw codecs only

[bryan.kewl]

and what are the minimum server specs to achieve 25 agents on outbound for the following specs
-hosted everything on one box, coding: g729, ratio: 1.3, with recording
-hosted everything on one box, coding: g729, ratio: 1.3, without recording

I don't want to get top-of the line server for the same purpose which a mid-range server can perform.

[Op3r]

It's boils down to being responsible and having a stress free VICIDIAL operations.

Think as an IT Manager of a more than 100 seats call center.

Do you want the whole floor to go down if you cram all your seats to a single Asterisk server or do you want to have at least 75% of floor working while you reboot the server that are being used by the other 25%?

[bryan.kewl]

@Op3r, I agree that its good to split load on multiple nodes/servers, but multiple nodes also require more time and effort to manage.

I am myself a consultant, web-developer and also manage servers. Mostly clients asks for a PD and also wants the cost as minimum as possible, so I want to know what specs are enough to manage 25 concurrent agents. Even sometimes clients ask for a small box to handle up to 20 agents or even 10 agents.

I don't want to recommend them big servers like dual-quadcore which may exceed their budget.

[Op3r]

If I remember correctly VICIDIAL group had a hardware guide released before.

But basically the gist is this.

Get the most powerful server you can get your hands on for the database server and just use a quadcore with 4gb of ram for asterisk servers.

for a single server with database,web and asterisk a quadcore with 4gb memory and a huge/fast hard drive can support upto 15 seats doing g729 and recording. Put in more seats than above that and say goodbye to your youtube watching habit while at work.

A lot of people may ask WHY U NO MAXIMIZE RESOURCES U HAB? You can always tell them DUDE YOU ALREADY SAVED SO MUCH MONEY ON AN OPEN SOURCE PREDICTIVE DIALER. Operating a Call Center company is not cheap nor a hobby, you already saved 1000 usd per seat license if you chose to go to alternative route. At least invest some of that savings in getting an over the top hardware to house that software where you will depend half of your company's income that it will generate.

A lot might get angry in what I am about to say. These cheapo companies who will not spend nor invest at least a decent amount of money in making sure that they will deliver a good service to their clients deserves to have multiple downtime and malfunctioning VICIDIAL system.

In short. VICIDIAL Open Source Call Center Suite is free, Stable, Full Functioning and Stress Free VICIDIAL systems still requires investment on hardware and management.

[slider]

A lot might get angry in what I am about to say. These cheapo companies who will not spend nor invest at least a decent amount of money in making sure that they will deliver a good service to their clients deserves to have multiple downtime and malfunctioning VICIDIAL system.

I couldn't agree more.

[gardo]

The 25 seats per agent "rule of thumb" was more appropriate when the most common servers available were dual and quad cores. It's no longer applicable today given the power and flexibility of modern servers. We've been running 80 seats outbound on a dual quad core Xeon, 8 GB of RAM, SSD RAID1 paired with a database server. Full recordings enabled and using g729 as codec.

Given today's modern hardware (32 cores, 64 GB RAM, RAID 10 SSDs), it's more cost-effective building Vicidial and Asterisk based systems than before. Less servers but more capacity.

[mcargile]

Hardware is not the limiting factor. Asterisk is. Asterisk has a large number of locks in it. Some of which increase exponentially the more channels you put through it. The big problem is that the locking causes issues that are not easy to identify right away. You can build a 32core dialer with massive amounts of ram and SSD drives and only load it to 20% of its total load and have problems. Calls will not connect properly. Calls will not log properly. The only real way to tell there is a problem is to trace a call from beginning to end.

We recommend using quad core processors, 4 to 8 gigs of Ram, and two hard drives in a raid 1 for your dialing servers and to load 25 agents doing outbound dialing. This seems to be the sweet spot for asterisk 1.4. There is no telling at present what Asterisk 1.8 will be capable of handling.

[gardo]

Asterisk is not the only limiting factor. It should have been both software and hardware. Hopefully Asterisk 1.8 doesn't have those "locks" that are so prevalent in 1.4.

A 32core dialer system with tonnes of RAM and SSD will be sweet. This can be virtualized to run multiple instances of Vicidial "bypassing" the "lock" problems of Asterisk 1.4. Doing the traditional setup (25 agents per server) is the real limiting factor IMHO.

[slider]

mcargile is right. a huge system isn't going to do you any good on asterisk 1.4. vicidial is realtime (mysql, apache, asterisk). that being said you need very low latency across the stack.

most people will realize issues scaling above a certain number of seats. the only way to fix this is to go back to the guidelines stated in this thread.

this will probably get better in asterisk 1.8 but it will be far from perfect.

[gardo]

FYI: We've run Asterisk 1.4 with more than 500 simultaneous channels without issues. Others have also have done it. There are also ways on how to maximize a "huge system" as I mentioned in my earlier post by virtualizing the system. By being more creative and innovative you can find ways on how to make a "limited system" more efficient.

[mflorell]

I had Asterisk 1.4.27.1 running over 1000 channels(mostly IAX) once, but it was not rapid predictive dialing, and trying that with SIP crashed pretty quickly. This is the exception of course, and the recommendations are based upon a "safe" number.

[Acidshock]

Has anyone thought about going the opposite way? I have been experimenting with quite a lot of success with smaller boxes running less agents. I have been using 1U rackmountable atom servers from super micro. They handle about 150-250 calls with about 6-10 agents on them. My overall expense is about 450 per complete box with IPMI! They use significantly less power too, which as many know... power is more the issue at datacenters compared to space. The additional advantage is that it enlarges the cluster, which can be a good or a bad thing... I think of it more in a good way though since if one box goes down not everyone takes a hit.

[gardo]

Yeah. 6-10 is a safe number on these dual core atom servers. It would be very interesting building a cluster of these energy efficient servers. Kinda like a small cluster farm of atoms.

[briansmith84]

I get extremely frustrated with seeing these posts.

I have 40 agents (half our floor) running on this single server:

Xeon E3-1270 3.5ghz
4gb ram
64gb SSD (everything installed on this)
500gb (just recordings, and by the way, all calls are recorded)

Server load averages at 4%

Now, FYI for those of you. This works flawless and have been running for a month with no issues

[gardo]

That supposedly rule of thumb was actually for older hardware or for servers manufactured under year 2010. We have been running more than 100 agents (g729, full call recordings, 3:1 dial ratio) in a server (dual quad core, 16 GB RAM and etc) in a GOautodial/Vicidial cluster. It really depends on how you optimize and configure your system. Not to mention how to bypass the limitations of Asterisk 1.4.X.

[mflorell]

It's not really a rule of thumb, it's a recommendation based upon a lowest common denominator, usually an older single-CPU system, and yes, we still run into new clients trying to cram as many agents as they can on a 6 year old Dell workstation. We had 100 agents on a single server back in 2006, so of course it's possible, but the number of agents a server will support is based on a lot of things, the lead quality, the lines to agent ratio, the inbound/outbound mix, the codecs used, whether you have dialing-only servers, etc...

[gardo]

Perfectly true!

It's not really a rule of thumb, it's a recommendation based upon a lowest common denominator, usually an older single-CPU system, and yes, we still run into new clients trying to cram as many agents as they can on a 6 year old Dell workstation. We had 100 agents on a single server back in 2006, so of course it's possible, but the number of agents a server will support is based on a lot of things, the lead quality, the lines to agent ratio, the inbound/outbound mix, the codecs used, whether you have dialing-only servers, etc...

[briansmith84]

I really want to stretch it to 80 just to see what happens

[williamconley]

Best bet is usually to have a second server clustered in and tested, then push the original server to the limit and see when it breaks. At that point, back off and put some agents on the second server ... but now you have an idea of how far you can push it without having to send anybody home when you find your barrier.

[briansmith84]

Some say thought that to cluster it has to be 3. Not true??

[williamconley]

Not true. Vicidial clusters can have two or more.

Use Vicibox to build the cluster. Works very nicely. Practice in VMware if you're nervous.

[mflorell]

The largest single cluster that we have built operating off of the same database was 26 dialers, 4 web servers and 1 master database and 1 slave database. This was an older setup that was capable of handling 350 agents and placing over 1.5 million calls per day. With the better hardware available today, you could duplicate the requirements of that cluster with a lot less dialers.

[lvish]

Hi

Will the agent capacity per server increases if I use asterisk 1.8 ? any body tested Vicidial -- asterisk 1.8 with 250 + channels?.

regds

lvish

[williamconley]

I expect more stability which of itself would imply higher capacity. But not the way you seem to be looking for. It may make it possible for another agent, but not 25% more agents. Don't forget that later applications also have (generally) more overhead and as such require more resources. So ... less crashes all the time, but not necessarily more agents unless you're already pushing the envelope. Then perhaps one extra before something breaks. Or perhaps less if the overhead is that much higher.

We have a few clients using it and so far have not noticed an increase in capacity.

But there are likely some taking advantage of modules not available in earlier versions of asterisk. I believe there may be skype/google voice/etc modules available. We have not yet checked.