Backup hard drive

For me, I use USB-base hard drive for backup as my main "go to" method. In addition, I also have RAID 1 - NAS and Time Capsule for additional data backup/sharing.

I do not care about the back up speed, as the "reliability" is my concern.

However, all of the USB hard drives (the 2.5" USB power) and (3.5" with external power brick) can do the job, with a grain of salt - because all mechanical drives will fail in the future (my Murphy's Law Firm has gave me few curses).

You might want to consider 3+ times size of your hard drive for the external back up space.

If you can afford it, I would really really recommend -- duplicate TimeMachine Drives (more than 1). Nowadays, 2.5" portable drive are less expensive and would not take too much space.

Some users here might also suggest a "bootable" backup. It's all up to you.

Apple does not suggest any in particular.

Most of the recommendations from other long time users point to OWC - www.macsales.com

Their Mercury Elite Pros (and Mini versions) drives and enclosures are excellent compared to cheap drives and enclosures which tend to fail from WD for instance.

You can use Time machine and yes, the size should be 2 - 3 times of your hard drive.

However, as a second backup solution - and my preferred solution - is to get an external drive and download either CarbonCopyCloner or SuperDuper in order to make an exact clone of your system which will be bootable. If there is a problem with your internal drive, you can simply plug in the external with the clone, boot from it, and keep working. It is also especially helpful if you upgrade and find that you have a problem with the new OS. Having a clone will enable you to "downgrade" and wind up with the system you had before upgrading. I have at least two clones of every Mac OS version I am running (four of them).