A CD is around 700Meg at most so the space goes faster than you might think. It's always best to have a backup drive on hand incase you run out. Considering the expense of setting up for the session and the people's time, you might want to have 2 backups available.
If possible you want to mic every instrument separately (several for the drums) but also include mics to record the instruments from a distance getting some of the room sound recorded. You'll at least want to use a pair of mics or a stereo mic over the drums but additional pairs of mics can be great for pulling the intimacy of the event onto the recording.
When you're close mic recording more than one instrument at a time, you invariably pick up the sound of the other instruments. The other sounds are relatively faint but come through on many tracks so there is a build up. Drums are usually the biggest problem since they are often loud and don't have a built in volume controls so you want to put something between the drums and the other instrument mics to minimize this (see the Sound Isolation Materials section below.
Vocal channels pick up the most bleed so you want to isolate the vocal as much as you can without killing the vibe of the band. The vocal track is EQ 'd and compressed differently than the drums so you want to minimize the drum bleed into the vocal mic. A good place to start is to face the mic directly away from the drums. In this case you end up with the sound of the drums bouncing off the back walls instead directly. Still not good, but a big improvement.
A common recording technique is to record a scratch version of the vocals live which gets replaced with a fresh track recorded later.
Refer to the Recording Vocals page for more info.
The sound of a bass guitar amp can leak into virtually every track. The result is that you have to turn down the sound of the clean bass track in the final mix leaving you with an inferior bass sound. For live ambient recordings, this isn't a big problem but for other close-mic`d recordings, can ruin an otherwise great live recording. Refer to the Recording Bass Instruments page for more.
Electric guitars will definitely bleed into drums and vocal tracks. When recording live in the studio, either close mic the guitar and keep the volume on the low side or put the guitar amp, and possibly the guitarist, in a seperate space. Another room or closet is best. Another room gives you more choices about where to place mics and room sound but a closet will work in a pinch. A dedicated room also gives you the option of having the guitar and guitarist in the room with the amp so you'll get some acoustic feedback. Fernandez guitars do this electronically ("Great stuff." - BobSellon ).
Since you are trying to keep the sounds as insulated as possible, some of the musicians may opt for a monitor mix in headphones. Cheap $20 phones will do the job but it's really worth upgrading to at least $80 phones if you can. Even iPod phones can be used but pay attention to any bleed that might be coming through onto the open mics in the room.
You'll also need to have some way of powering those headphones. You can often take care of this on-the-cheap by using the mixer output with a splitter or an old stereo (yep, done that), but if you do a lot of these types of recordings, you'll want to get dedicated headphone amps.
The tighter the space, the more bleeding you are going to be left with and, generally, the worse the room sounds. In a pinch you can use a wide variety of materials to improve isolation (see below) but nothing beats physical space. If one of the members of the band is producing/engineering the recording then you'll probably have some of the recording equipment in the same room you are recording with. If at all possible, use a desktop system (not a laptop) that can be put in a different room so you won't get fan noise on your recording (run extension wires for the mouse, keyboard, monitor and audio interface.
There are lots of great sound isolation materials you can buy but you can get a lot of mileage out of blankets, curtains, carpet and other fabrics. Fabrics absorb high and high-mid frequencies pretty well. Lows are tricky but, depending on the music, might not be a problem.
Mixing recordings made live in the studio depends a lot on the style of music and miking used. Also refer to the Mixing page.
For ambient recordings, you'll usually have one or more pairs of mics recording the room, drums and possibly other instruments. These tend to be sonically pleasing to the ear due to the acoustic mixing of the sounds. Artifically mixed music is often missing suble acoustic clues that the brain uses to process incoming sounds. If you want the final recording to sound like the band does live, it's best to record it that way.
A dry recording does not include any ambient(room) sounds or the sound of the other instruments. When creating dry recordings, bleeding from other tracks is a huge problem. Drums bleeding into vocals are death. Run a few test recordings before getting too far into the session to see if there are still any serious bleed problems. Noise gates and Expanders are often used to block sound from other tracks. Whenever possible, record without the gating and clean it up later. Getting the settings right can be difficult so you don't want to be stuck with a choppy recording due to a threshold being set wrong. Be sure to record at 24 bits.
Check the Bleeding section for additional info.
These are recordings that use audio effects to enhance the sound. Amost all music is recorded with some kind of compression, which is an effect, of sorts. Reverb and echo are well known audio effect as are flanging, phasing, tremolo and virbrato. There are endless variations on these and more.
When dealing with close miked drum recordings, you are constantly battling bleed from one drum to the next. Drums generally sound better when miked with an over head stereo pair panned slightly left and right (25-50%) using the close miked tracks to augment the sound of particular drums. If triggering is not used, you'll usually want to "gate" or "expand" the tracks to reduce/eliminate the bleeding the process the resulting signal: echo, reverb, EQ, etc... Refer to the Recording Drums page for more info on mixing drums.
Vocals are brutal in live-in-the-studio recordings because they tend to pick up the sound of everything in the room and, usually, badly. You get drums but they sound like crap. You bring up the vocal channel and the mix goes to hell. To make matters worse, most vocal tracks sound much better if they are compressed and EQ`d, sometimes dramatically.