what is a bootable backup and do i need one? what are partitions good for?

SilverKeeper gives the option of cloning a bootable backup. i'm not exactly sure what's the advantage of this and in what case i may need it.

A bootable backup is an exact copy of your hard drive's contents on another drive, that can be used for booting up the machine. The advantage of a bootable backup is that, in the event something bad happens to your internal drive, you can very quickly get up and running with the backup drive, and can copy that back to a replaced/fixed internal drive very quickly. Time Machine backups are not bootable.

The disadvantage of a clone of any kind, bootable or not, is that there's only one version of any particular file stored. So if a file gets damaged and then backed up, you're pretty well screwed with the clone, while Time Machine stores many versions of the file, so you just "roll back" to the last working copy.

when i got my last computer i was able to transfer everything from the old computer, including applications, to the new one without having to find all the serial numbers and reinstall them.

Bad idea... while this will work for most apps, different machines have different architectures, so some apps may not be installed correctly for the new machine, plus you may not have properly copied some components. You should have reinstalled them.

i thought that time machine will be able to do the same thing if i lose all the data on my computer. is that not so?

If you have Time Machine back up the entire hard drive, without excluding anything, then Time Machine should be able to restore your drive to exactly the way it was at any particular moment in time at which it made a backup, including apps, system files, preferences, etc.

my other question is what are the advantages of making partitions in my new drive (i understand i have to if i want a bootable backup, but is there any reason to partition otherwise?

You do not have to partition to make a bootable backup. However, you'll be using the entire drive... trying to store additional files on the same drive as a bootable clone is confusing at best. Using a partition allows you to create multiple "virtual" drives... say, one for a bootable backup, one for a Time Machine backup, one for movie files, etc. Of course, this is only advisable if the drive is much larger than the one you're backing up, and note that if you store original files on a partition (like a bunch of movie files), you need a backup of those somewhere else.

Time Machine will want it's own full drive or partition to play with, which should be larger than the drive being backed up, and will eventually fill it. A bootable clone probably also should go onto its own partition, but you wouldn't need to make this partition larger than the drive being cloned. Other than that, don't worry about partitioning unless you have a specific need.

dndn wrote:
is storing files on a partition less safe than storing them on an undivided external drive? or is this a general suggestion for backing up original files in more than one place?

Partitions are nothing more that different sections of the SAME hard drive. So if you had a drive partitioned into two parts so that it shows up as two drives on your desktop, it is still a single hard drive. If your hard drive physically fails, you lose BOTH partitions. So anything you copy from one partition to another is not a true backup with Physical HD issues.
You can reformat one partition if needed and then copy things back to the newly formatted partition from the other partition, so that is sort of a "soft" backup. But for true backing up of important files, you really need to do this on a physically different hard drive.
Patrick

"if you store original files on a partition (like a bunch of movie files), you need a backup of those somewhere else."

is storing files on a partition less safe than storing them on an undivided external drive? or is this a general suggestion for backing up original files in more than one place?

Just a general suggestion. Many people tend to make the mistake that, if a file is stored in the backup (or on the backup drive), they don't need to have it anywhere else. Of course, then if something happens to the backup drive, there goes the only copy... and you can be assured that, sooner or later, something will happen to every drive.

dndn wrote:
if i understand you correctly, the bootable backup is not so much for restoring my computer software and data (that time machine can do that) -but more for the option to keep on working immediately in the event my computer crashes

Both can restore your hard drive to the conditions at the last backup. The big differences: a bootable clone is bootable for quick and easy access in an emergency, a TM backup is not, and a TM backup can restore multiple different "versions" of your drive (from different times in the past), while a bootable clone only gives you one.

or for booting my computer on someone else's computer?

That will only work if it's exactly the same model. It won't even boot someone else's MacBook if it's from a different "generation" than yours.

PT wrote:
1) In the event your internal drive crashes, you can either boot of the clone and keep working until your internal drive is fixed.

Be very, very cautious with this one! If your internal hard drive dies, your backup drive becomes the only copy of everything. If you then start working from that backup drive, and something goes wrong there, you've now lost everything. You'll need to make sure you've got a backup of the backup before you start using it.

(It's safest if you have multiple redundant backups, with at least one stored off-site. I have three, with one stored in the safe deposit box at the bank.)