It's not a live show. It's a live recording session.

A lot depends on what you want to do with the recording.
 
I regularly record the rehearsals of one of my bands. I started out mic'ing all the amps, putting up one drum overhead, and getting the keyboards and vocals from an aux feed from the PA mixer. 
 
More recently I've found it simpler and just about as good to put a couple of LDC mics up in an XY configuration in a corner. 
 
But this is meant to be something that the band members can listen to later to review the rehearsal. If you're looking for a more professional recording, I don't see how you can do it without headphones.

Recording a band 'live' can be done, and some very good records have been done that way. And many more not so good ones.

I've not recorded anyone that way in years, but a band I was once in recorded a demo/something to sell at gigs that way and it worked well enough. Here's how it was done -

Crosstalk is the big enemy, followed by feedback, followed by phasing problems (caused by crosstalk).

For the drums use as few mics as possible, try the method used to record John Bonham using three or at the most four mics. Surround the kit with baffles to keep spill down, no drums in any monitoring, they're loud enough already.

Guitar. Use a low-wattage amplifier if amp distortion is required. Remember that 5 watts is very loud in a small room, typically about half the volume of a 50 watter. Put a baffle a few inches in front that's only slightly taller than the speaker so the sound reaches the room. Single mic, close to the grille between speaker and baffle. If the amp's got an open-back speaker cab put an absorbent baffle behind that as well to reduce reflections.

Bass is approached in a similar way, probably no need for a low power amp, just keep the volume down. Consider using a DI feed instead of a mic if the bassist's OK with that.

The guitar and bass speakers should face each other across the room and the mics be directional, with their least sensitive side facing the speaker across the room.

Vocal mics need to be directional as well. A screen to block sound from the sides and rear of the mic is essential and have the singer facing into the band so everything else is in the mic's least sensitive zone.

Foldback, vocals only and as low a volume as can be made to work for the band.

And you need a room with at least one, better three, really dead walls.

Then, if everything is optimally set up (which takes ages) and no-one plays a duff note you'll get a recording. Things might need moving around after the first take if there are phasing problems between tracks caused by sound-spillage.

If that sounds like a lot of work, it is.

If the band can play in a balanced way regarding volume then I'd try just a stereo pair of mics instead, and again only use foldback for vocals, with the foldback speakers pointed away from the mics.

You'll lose a lot of control over the mix whichever way you go.

I don't have time to type out how I do this style of recording right now ,, but you defiantly asking for trouble with what you are describing. 
First, huge mistake using live speakers ( PA and AMPS)  in anything but a recording of a live event. 
It can be done as in TLW method described above, that's certainly one way. 
The success of that recording will be hugely dependent on the space used. 
If an ideal space is not available then you really need to go with headphones or in Ears or a mix of both. 
 
Any how, tell us what your goal is for this recording and what equipment you have on hand and there are plenty of us who have years experience with this and can help you make a killer recording live off the floor. 

You asked so here's my story.  I bought a new laptop and a Roland Studio Capture when the motherboard of my trusty home build desktop fried.  My rock solid emu 1820 PCI card, which I have been using for over a decade, probably 2, came with sonar 6, or earlier.  I have upgraded sonar through the years and have been merrily making home recordings on my own with occasional sit ins with friends and band mates in my basement at friendly volume levels with a reasonably good room.  No real issues.  No one on the forums probably knew I existed.
 
I play bass in a 70's classic rock cover band that likes to play anything from Bread, Derrick and Dominos, and Van Morrison to Deep Purple and Bad Company.  When practicing at my buddy's house, we just run the vocals through a simple pa head and wail.  Lots of fun but ears are ringing by the end of the rehearsal.
 
Now with the new equipment and its portability, I take the new equipment to practice, I plug it all in and nothing but feedback.  Most likely I didn't realize the echo input monitoring was on.  However, if that is the immediate problem,  I can just turn the input monitoring off and not send signal back into the room via sonar.  I'll listen in on headphones myself, and I can at least get something recorded. 
 
Now all of the other advice comes into play to get a good or if I am capable of engineering it, a great recording. 
 
I want to record the rehearsals for learning purposes and I want to record our gigs to make demos to give to new venues to land new gigs. 
 
 
The goal for recording the rehearsals is to tighten up the band and improve vocals. More importantly to bring the sound level down.  Right now sloppy timing and unbalanced, sometimes off key vocals are being masked by playing too loud during rehearsal.  Sound familiar? The room is a basement setting with 70's era wood paneled walls.  I want to record the rehearsals in a less than optimal room with a bunch of players that I need to reign in.
 
The band uses the following gear:
Rhythm Guitar:  Fender Roadmaster 50 watts. 
Lead: Marhshall 50 watt combo.  Direct emulated out on this.
Bass:  100 watt Peavey.
Keyboard 50 watt Roland amp. 
Tama acoustic drums.  
 
I have available:
Roland Studio Capture:  12 combo XLR inputs and the ability to output to mains and four independent monitor mixes.
Five DI inputs via one a Behringer DI red box, and a Behringer Ultra DI Pro which provides the other 4 DI's.
A four channel headphone amp (Behringer Power play Pro- XL)
A Crate 24 track analog board
A Behringer 1832FX Pro analog board. 
2 Yamaha 12" wedge monitors
2 Yamaha 15" main speakers
A full set of drum mics with 2 condenser overheads
A bunch of Shure SM 58's for vocals and micing amps.
 
The goal for recording live gigs is to use sonar make demos to land other gigs. Ideally, I want to record the gig by routing everything through the Roland Studio Capture.  Record all the instruments and vocals live realizing there are foldback issues with the vocals and drums.  Then send the vocals out to the live pa. The amps for guitars, bass and keys are more than enough to fill any room we play.  I'd like to send the snare and kick out through the pa as well.
 
First I'll make the boys ante up and get headphones.  This is the easiest way to get things going in the studio/basement.  I'll mic the  amps with sm 58's and put baffles around as described. mic the drums.  Send nothing from the amps or drums (never do) through the PA and send only vocals to the pa until I can get the boys to buy some headphones.  Funny how a bunch of successful middle age guys balk at coughing up fifty bucks or so to improve.
 
I also appreciate the tip of not letting anyone hear the product as no one is going to like the raw product from the rehearsal recording. 
 
Playing out at small venues and making a killer recording of same using the equipment at hand is the goal.
 
This forum is a great space for those who want to go further using sonar to make music and enjoy themselves.  All the advice is greatly appreciated.  I know many of you have years of experience which I truly value.  I'm not that savvy when it comes to this and reducing my learning curve with the input of everyone's valuable time really makes takes the experience to another level.  Thanks!

Recording for your own reference and recording a demo are two very different things and I wouldn't try to mix them. You'd be spending a lot of effort for little benefit either way. Practice, record references and improve yourselves first. Then book a day to record everything in isolation. If you're playing with click you could maybe prerecord a guide vocal and bass part at home. Then do the drums and continue from there.

Of course recording live gigs is fun, I don't think I really understand why you would want to run everything THROUGH Sonar. Normally it would be preferable to use the live desk direct outs if you want to multitrack. Otherwise you'd always deal with latency or, worse, pops/crackles or dropouts if you're unlucky.

brekus1
I'd like to send the snare and kick out through the pa as well.

I'd want to be certain they're not carrying OK before doing that. Both need a lot of headroom to avoid distortion, and kicks can shift a speaker cone like little else. Lots of power needed.

brekus1
First I'll make the boys ante up and get headphones....... 
........Funny how a bunch of successful middle age guys balk at coughing up fifty bucks or so to improve.

No, it isn't. Some people who aren't in any way short of cash won't even spend money to replace malfunctioning gear and resent the cost of every string or pick they buy. Been there, done that, got the T-shirt and sacked the offenders/walked out of the band.

As for using headphones, it'll be something new and different, expect some resistance and having to do a lot of gently and diplomatically getting them used to it.
 

brekus1
Playing out at small venues and making a killer recording of same using the equipment at hand is the goal.

If possible I suggest taking a 'sniff' out of the mixer channel inserts might be the way to go. It's done by inserting a standard mono (TR) jack lead, rather than the usual TRS insert Y lead, part way into the insert socket, until you hear/feel the first 'click' as the tip passes through the first tip contact. With any luck that will give you the post-pre amp, pre eq, fx, fader etc. signal from the channel while still letting the signal through the channel normally as well. If so, hook up the other end of those leads to the Roland interface and job done. Each mixer input fed to its own track in Sonar.

If that doesn't work then a cheap patchbay may do the job. One that's 'normalised' on each pair of sockets on the front and also can feed whatever comes into those sockets to another socket that's usually on the back. That lets you hook up a normal insert Y lead, the signal leaved the channel, goes to the parchbay and comes back again through the normalised side. Another jack socket then allows you to tap the signal without disturbing it. Behringer make (or used to, don't know if it's still in production) a very inexpensive jack patchbay that is/was very good value and makes this sort of thing easy. If you use the inserts for processing audio then it's time to maybe look at a mic splitter to do the job by splitting stuff before it reaches the mixer (how venues with mixers for front-of-house and another, usually at the side of the stage, for the foldback mix do things).

If the audience is enthusiastic, put a mic or two near the front of the stage pointing at them and record them as well, then mix it in to give some atmosphere. I think the trick with that sort if live recording is to capture the feel of a really great gig at least as much as it's about hi-quality. And when you discuss it with potential bookers never start by apologising for poor audio quality, just say it's a rough mix off the live desk, here you go. :-)

If all else fails, just using a couple of mics at the back of the room can be effective. Or if you do any gigs where the venue does sound, see if they can take a recording off their desk for you. Even offer to use your own laptop and interface if necessary.

I would use something simple to record practice.  I used to use a cassette recorder (two small microphones for stereo) back in the 1990's.  You are trying to set a reference of the sound at a particular point (where people are standing.  You cannot get this by using an interface.  use a portable recording device (yes even a cell phone will work).  Some of the new digital cameras will to, but use caution you may overload them and damage the mikes.
 
Have each person record their own position with their phone.  That way you will hear things from the other people in the band's perspective.  It may not be the cleanest recording, but that is not the purpose.  The purpose is to let everyone hear what you are hearing and vice versa.  Lower stage volume is the key to letting everyone hear what they need to hear. 
 
 
 

I am not familiar with your audio interface, but since you seem not to be using a monitor mix, the easiest way to avoid any feedback looping is to mute some of the tracks you are recording within SONAR. This can get tricky using the house speakers during performance, so take a good look at that. Anything not going to the house speakers for performance purposes can be muted within SONAR during tracking.
 
For a start, look at the tracks which get "immediate intense feedback" when armed, and mute them. They will still record muted.

I do this a lot. I run the sound for the band while catching the recording.

It helps that I am not performing when I do it.

I can share some MP3 examples if you like.