external drive to use with time machine

Personally, I would purchase separate enclosure and drive.

This approach allows you to select the level of quality of each.

Generally, the off the shelf "packaged" drive will often have poor

electronics to interface the drive itself to the computer and the

actual drive contained within them will typically be lower grade drives.

OWC is a good choice for enclosures (https://eshop.macsales.com/shop/hard-drives/External-Enclosures).

Personally I have had very good success with the all aluminum StarTech

enclosures which are available most anywhere (Amazon, NewEgg, etc.)

As far as drives themselves, the basic rule of thumb I have always used

is that the backup needs to be the most reliable part of any system.

To that end, when selecting a drive, choose one that has the longest

warranty. A five year warranty drive will be better than a three year.

One thing to note, standard hard drives are mechanical and as such,

can fail "out of the box", last beyond your computers usefulness,

or anywhere in between.

I use the same plan as woodmeister offers. He is wise.

I buy empty OWC Mercury Pro enclosures for 3.5-inch drives and install the higher-grade Western Digital "Black" series drives. My iMac has two: one for Time Machine and the other for bootable Carbon Copy Cloner backups.

Before that, I had trouble with most "name-brand" external enclosures. Their design criteria appeared to be "something that can go on sale every other weekend" rather than what I need: works-every-time reliable.

As for price, yes you will pay more for the security and reliability of the OWC drives. The pain goes completely away when I ask myself, "How much is my data worth?"

For a desktop computer I strongly recommend the larger 3.5-inch enclosures with an independent power source because:

1) cheap "bus-powered" drives (must get all power from the computer's USB port) can sometimes fail to get enough energy from the computer as their drive motors age.

2) Historically, the larger 3.5-inch drives are more reliable than the 2.5-inch drives installed in "portable" enclosures.

Also, remember that most preassembled drives you buy at the local office superstore are pre-formatted for Windows. Even those sold as "Mac Editions" often have odd, proprietary formatting. WD are bad about doing that. If you must buy one of the "lesser" drives and do not need to share it with a Windows computer, use Disk Utility ( in the folder path Macintosh HD > Applications > Utilities ) to erase and reformat the drive to "Mac Extended HFS+ Journaled) before using it.

Do not install any software that comes with a preassembled drive. Most is useless on a Mac and can slow you down.

Hi,

I'm using self powered external HDD(2TB) as Time Machine drive.

It's working quite well.