Best back up plan?

I'll save my session after every couple takes.

I'll back up the session and WAV files to an external HDD after every couple days in the studio.

I'll burn the session and associated files to blu ray discs after the project is done. (I think the best option is to back up to multiple formats)

I've only had a total HDD failure once about 12 years ago on an old PC I let get infected with a virus(the recording computers no longer get on the network/internet in my studio).

I suppose folks could back up to the "cloud" too, but I'm not getting on the internet with my recording computer for that.

I save a separate folder for every artist and I include all session files, audio files, imported audio, etc.  Everything I need for that project goes into that one folder.  When it comes time to back up I just copy the folder to the external drive.  

I also don't compress files or folders, I don't want even the slightest possibility of losing any data, so the less data manipulation, the better.

I have 3 portable back up hard drives, hit save often enough that it wears out my keyboards, I have a back up and redundant back up within the computer and I have Carbonite I save to as well. Lose one project and it makes you over do the back up. I had a lightning storm come up fast here as I was backing up a project once. I decided to let it roll and get the record backed up after the final mixes were approved. Lighting zapped both of my Belkin battery backups, my mother board, power supply and misc computer parts along with the record I was working on and the two backup drives I had going all got wiped. One of the worst days I have ever spent in a studio. Luckily, I had all of the raw tracks and was able to remix it in a few days. There was less than 30 seconds left for the backup to be finished and I was going to shut down. Major lesson learned. That was close to 10 years ago now. I hope I never see another day like that one was.

Like others, I hit Save regularly.  I use Carbon Copy Cloner to back up the project drive to an external drive after every couple of hours during a session.  (only backs up new data, so we're talking under a minute.)  Lately I'm using Seagate Slim USB3 drives that are powered by USB.  I only keep the backup drive plugged in when I'm backing up for reasons already discussed!  Once I'm deep into any particular project I'll make another copy too and keep it off property in my Dad's closet.  Eventually I'll probably do the cloud back up thing, but this works well for me.  CCC is also great/simple for making a boot drive clone.  

I used LaCie's freeware for many years but it's now obsolete. It was very simple and stable. Loved it. CCC seems advanced and packed with features, but is it simple to use for the simple everyday tasks? Simple to setup for backing up individual folders, only updating new files?

I use four drives in my PC

One SSD for keeping my DAW's, the 2nd for Mirroring it. A third SSD for storing my sessions, keeping my plugin library, and samples. And a FOURTH SSD to mirror all of that stuff. Basically if something happens to the two primary drives...you always have a backup drive which has copied every single change in real time as it happened to fall back on. Lastly I change externals every three years.

How many of you have used Backblaze?
Seems a lot cheaper than a 4 bay Raid5 array

iMac system drive is Time Machined daily.

Session files are stored on an external LaCie drive and backed up to a second LaCie drive.
Additionally we are adding a NAS (RAID) which will be inside the main house and networked via underground CAT6 back to the studio (about 75 feet/25 metres)

Finally a portable laptop drive will be utilised for offsite storage.

iMac is on a UPS and a second UPS will be used in conjunction with the NAS.

is it really unlimited?

I track to a 2nd hard drive built into the studio comp. I have each artist purchase 2 hard drives before the start of the session. At the end of the first day, everything on my drive is copied over to the 2 external drives. Each subsequent day, I sync up the drives at lunch break and at the end of the work day with a program called Chronosync. I think its one of the best tools in my studio and I use it at home as well - fantastic program.

When the project is finished, I keep a hard drive, and the artist keeps a hard drive, so the data is always in 2 places. I keep the project on my studio hard drive for 6 months in case of any recalls and then I remove it for space.

In PT, I have it set to auto backup every min, and it keeps 99 of the backups. I'm pretty religious about constantly hitting the save button after ever few moves, but the session file backup has saved my ass every now and again when I've had a system crash, power out, etc.

I HAVE screwed myself in the past while mixing on the SSL. At mix stage I'll run PT from the SSL transport and turn the screen off so I don't even think about anything with the computer. I've gotten so "into" a mix that I've gone 3 hours without saving automation etc on the console. Big mistake when the power went down and I lost that many hours of rides when I felt I was about an hour out from being finished with "the best mix ever" hah!

Not sure if the is a good way to do it but I save every 30-60 minutes or so if I'm working on a track, I keep all my tracks on a separate Glyph drive, with one backup per day to Logic, which gets copied to Time Machine once a day.

A sidenote on SSDs for backup.
It seems like a great idea to backup projects to SSDs and then put it in a safe storage room. They are small, became affordable, have no mechanical parts that could make any trouble.
Well - it is no good idea.
Tests have shown that many SSDs start to "forget" when not connected to a PSU.
This starts already after just a few weeks and will undoubtly lead to more or less severe data loss.
It was quite a headline in IT world, because absolutely nobody expected this desastrous result. It makes them unusable as a serious backup method, even for system drives.
A workaround would be to leave a backup SSD in the computer case and just connect the PSU.
But in worst case, and this is what backups are for essentially, if something shoots from the mains thru the PSU, everything connected can get lost. Been there...no fun.