Bootable backups - disk utility and which external drives

Question

hi all
(maybe) a simple question
i have been using time machine for my back ups but i am now planning to have a second backup program. i'm looking at using a bootable clone in this regard.
i started looking at super duper and ccc however a few stumbling blokes have just popped up (well at least warning signs that may be of no issue at all - hence this question)
* can ALL external drives be used for bootable backup purposes?
I have a couple of western digital ones - my book essential and my passport.
On the western digital website, it does not have my model numbers listed - does it matter?
Is it a case of any usb connected external drive can be used for intel macs? - i am getting conflicting views on various postings i have seen re this question
second part/question is:
i also understand disk utility can be used for cloning (no updates, just full clones) and as a bootable back up.
if, just for the purposes for having a back up bootable drive, can i set up a clone without too much regard for recloning it (say every 2 months) and if i need to use it, then boot the mac back up with it and then do a full restore using my up to date time machine backups? am i missing something with that method? is that too simple?
feedback much appreciated on these 2 areas
cheers
peter t

Answer 1

Crows2012 wrote:
1) there is no way to make a BOOTABLE clone using disk utility or time machine whatsoever, right? DU will only allow me to make clones and Recovery HD essentially allows me to restore the system (ie software) AFTER booting up?
Correct with respect to TM; all you get is a copy of the Recovery HD.
Disk Utility will make a bootable clone, but there are downsides.  First, it can only do a whole copy;  unlike a specialized cloning app, it won't copy just what's new or changed, so takes a long time.  Second, as I understand it, it won't copy to a smaller volume, even if there's plenty of free space on the internal.  For example, if you have a 1 TB internal with only 400 GB on it, DU won't copy it to a 500 GB drive.  I may be wrong, but I've seen that posted here by folks who seem to know.
does file b here mean aliases of file b in each backup?
It acts sorta like that, but no.
There's one copy of the actual file, but two hard links to it, one in each folder.  The file actually "belongs" to both folders at the same time!  The good part of that is, if you delete either backup folder, the other one remains intact.  The downside is, how the heck do you count the size of each folder accurately?
that was a great read to understand TM workings and attain some level of piece of mind re my question of incremental v differential backups
It is a bit hard to get your head around!    I've been revising and editing that for several years trying to make it clear.
And remember, this only applies to TM as far as I know, at least for consumer-level backup apps.
While it may be possible to boot your computer to an external hard drive, Western Digital does not provide technical support for booting your computer using an external hard drive. If you intend to make a copy of your boot drive, or install your operating system, please use a second internal drive (EIDE or Serial ATA), rather than an external drive.
Yup.  WD doesn't exactly have a good reputation for support. 
i guess i'll trial CCC or SD and see what happens with the drives that i have re BOOTABILITY
I use CCC myself -- it's a great product with great support.
I downloaded SD a couple of times, but never got around to experimenting with it.  Lots of folks swear by it, and say it also has excellent support.  To a large degree, it just seems to be a matter of which approach and GUI you prefer, but CCC does allow "archiving" of changed and deleted stuff (differently from TM), and can copy Recovery HDs.  I don't think SD does either, but it may have other advantages.
4) and, i think one final question, and a simple/naive one at that.....if my internal hard drive physically collapses then what are the benefits of that bootable clone v not having one?
You can start up from the clone and run normally (but likely a bit more slowly), although you probably won't be as up-to-date as you would after restoring to a new or repaired internal, or an external, from TM.  The reason is, running a clone backup, even an incremental one, takes much longer and far more CPU than one of TM's quick incrementals, which it will do hourly if you let it.  Few folks using a clone for an OSX drive do it more than once per day, many only once a week. 
The downside is, if you run from the clone, you no longer have a backup -- the clone has the only copy of your stuff.  That's one reason many folks who use only a cloning app have two (or more) externals with them.
Apart from (obviously) being able to start up immediately to do whatever i wanted to do at the time, after i replace the hard drive (if that was to be the case) are there further expenses or much inconvenience suffered due to not having a bootable drive in getting things all sorted internally on the mac? what is the process in that regard, generally speaking
Just clone the external to the new internal, and you're back in business.
thanks heaps for your time to answer these and previous questions and to build up my understanding of these topics
You're quite welcome.