I've got a couple of days off and am going to copy some of my libraries to a spare drive.
 
What is conventional wisdom here? Copy the rar or zip, the unzipped installer, or just the library proper?
 
How do you guys do it?

I keep the original downloads on hard drive and burn Dvd copies. I also make an Acronis image of the drive where they are installed.

Acronis full backups of all active drives. I have a couple external drives, one for each Acronis backup run. I alternate those drives as the target for an Acronis backup every other week.

Note: restoring from an Acronis backup has saved my bacon probably more than a dozen times already. Things can and do go wrong on an active drive. Very good idea to have backups.

I picked up a couple of 2 TB SATA III internal drives, and use them for backing up things like sample libraries.
 
Both drives have the same backup data on them - The 1st of the drives remains installed in the computer, while the 2nd drive is only plugged in long enough to update its backup data and then it is physically removed and stored off site.
 
A new 2 TB drive runs less than $75 these days.  I got each of my newest drives for $54 each on sale.
 
Bob Bone
 

Bob I also store at least one of my rotating backups off site. Just in case...

Storing off-site is most wise - I guess I'm stupid.    I just keep my backups in an allegedly fire-proof filing cabinet.
 
I do an image copy of my entire system at the first of every month using an external drive with USB 3.  I keep the last three backups because there's room for that many but no more.  Without the USB 3, this would be an overnight operation, but I can backup the whole system in about 90 minutes currently.  I'm pretty certain that my Kontakt content is at least half the data on my entire DAW system.
 
I also make a couple of DVD backup copies of the original downloads in whatever compressed format I got them (usually zip).  I don't store those off-site either, but I know damn well I should!
 
I picked up NERO (which I'm otherwise not at all enthusiastic about) because it has a convenient feature.  It will span large files across multiple disks and reassemble them when restoring them to the hard drive.  This can be an extremely convenient feature for massive Kontakt library data files.

Well, no backup plan is perfect, and there are some common sense self-imposed limitations.
 
My off-site storage is worthless if my corner of Maryland/DC gets nuked.  Or course, I would be vaporized, but point being is how far does one take their backup strategy?
 
As far as backing up data that doesn't change very often, I skip that.  My Kontakt libraries are almost always static - I do not add new content very often.  When I do, I back it all up, but otherwise, it exists on the local active drive, the internal backup drive, and on the off-site drive, but only gets backed up when sample content changes.
 
I use the same approach for Cakewalk Projects.  I keep a copy of all project folders on all 3 drives, but only back up the static projects to the internal backup drive once every 3 months, and to the off-site drive once every 6 months.
 
All new project folders get backed up to the internal backup drive as soon as I have finished the Sonar session in which they were created, then to the off-site drive on the 1st weekend following their creation.
 
Any project I am going to modify gets backed up to the internal backup drive prior to my opening the project up for modification, and to the off-site drive on the 1st weekend following its modification.
 
Non-Cakewalk documents and downloads and such get backed up to the internal drive every weekend, and once a month to the off-site drive.
 
It's really all about whatever makes sense to you - you are the one who best understands your work habits, frequency of change, and criticality of data.
 
Bob Bone
 

I prefer to make DVD backups and store them in the house. My biggest fear is somebody breaking in and stealing my computers, which would be disastrous if backups were all on a removable drive that went out the door with everything else.
 
I'm planning to acquire a proper safe and bolt it to the floor, for stuff that I want to keep secure but also keep handy (e.g. microphones). When I get one, the DVDs will go in there, too. Part of my motivation is that I forget where I've stashed things...my wife hid my passport somewhere in the house and I've yet to find it. I'm starting to get worried because I have overseas trips planned in the near future. If I'd had a safe I'd know where it was. All I have to do is remember the combination.

Thanks guys- you people seem to be much better planned than I. 
 
I don't understand computers and was wondering if I need to backup the installer or just the data which the installer installs. Probably it doesn't matter with Kontakt libraries. But I seem to remember that some VSTs can't just be relocated without consequence.
 
Burning DVDs? Is it accurate or are there writing errors? Some programs want to run a checker after the burn to identify any possible discrepencies. I think I prefer just having a not always connected harddrive dedicated to backup. The EastWest 35 double density DVD pianos kind of put me off DVDs for life.
 
Hope you find your passport Dave  I know the feeling. I'm forever losing my sunglasses and they are on top of my head.

bitflipper
I prefer to make DVD backups and store them in the house. My biggest fear is somebody breaking in and stealing my computers, which would be disastrous if backups were all on a removable drive that went out the door with everything else.
 
I'm planning to acquire a proper safe and bolt it to the floor, for stuff that I want to keep secure but also keep handy (e.g. microphones). When I get one, the DVDs will go in there, too. Part of my motivation is that I forget where I've stashed things...my wife hid my passport somewhere in the house and I've yet to find it. I'm starting to get worried because I have overseas trips planned in the near future. If I'd had a safe I'd know where it was. All I have to do is remember the combination.

You know, Dave - if you were to take off those shades (it's night now, but you still have them on in your picture), perhaps you would be able to SEE if anyone were breaking in to steal your computers and your external hard drives.
 
Bob Bone