Best disk format for use as Time machine external drive

Pedro,

*_How Should a Time Machine Hard Disk be Prepared?_*
For Time Machine to work properly, the hard disk must be formatted “Mac OS Extended (Journaled)” and its’ Partition Scheme should be either GUID or Apple Partition Map.

Time Machine is incompatible with disks partitioned as Master Boot Record (MBR). Unfortunately, this describes nearly every hard drive you can buy because MBR is a Windows partition scheme. (Naturally, this DOES NOT apply to Apples’ Time Capsule.)

For some, Time Machine begins to perform as expected with a new external hard disk. But then the initial full backup or subsequent incremental backups fail. The user only later discovers the hard disk was still partitioned as Master Boot Record (MBR).

One article on Time Machine made this observation: “Virtually everybody will have to open Disk Utility and repartition the disk as APM or GUID. It doesn't really matter which one because the Time Machine disk will not be bootable anyway. APM allows a disk to boot a PowerPC, GUID allows the disk to boot an Intel processor but both are easily digestible by Time Machine on either kind of processor.” [http://www.girr.org/mac_stuff/backups.html]

It’s been recommended by many here that your reserve +at least+ double the size of your primary hard disk, that way Time Machine backups have room to grow as the size of your data grows. Additionally, the more space you give Time Machine the more history it can preserve. The less space you reserve for Time Machine the sooner older backups & deleted items will disappear.

Procedure
Connect the hard disk you wish to use for Time Machine backups.
Launch Disk Utility.
It will appear twice in the pane on the left. (Make sure you recognize that it is different from the 2 icons that represent your Macs' internal drive.) The upper entry represent the device as a whole, including the controller inside. The lower entry represents the hard disk contained within the device.
Click on the upper icon of the external hard disk.
Select the "Partition" tab.
For "Volume Scheme" choose "1 partition". (Chose 2 partitions if you intend on storing other data on the disk besides your Time Machine backups.)
Name the disk.
Format should be "Mac OS Extended (Journaled)".
Click "Options".
Select either GUID or Apple Partition Map. (See above for significance)
Click "OK".
Click "Apply".
Now chose the level of secure erase you desire. (More passes means more time)

Once the external hard disk is repartitioned, select it again in Time Machine preferences and use it for your backups.

Let us know if this was helpful.

Cheers!

Pedro,

No, you won't need to "Erase" again. I have corrected my instructions and removed that step. Once you click "Apply" in the Partition Tab, Disk Utility will reformat your disk for you. You won't need to reformat again after this step.

Thanks.

Glenn

Pedro,

You can stop it. Just select "Erase" again but do not chose "Secure Erase". It will reformat it in seconds and yo can begin again.

It's possible to use DU on a disk connected to Airport Extreme (AirDisk) but your best option is to move the Hard disk back to the Mac, do your disk maintenance, then move it back to the Airport Extreme.

Glenn

Pedro,

Move it back to the USB port on your Mac, it will not work on the USB port of the keyboard. Now reformat the disk again.

From my experience with using USB hubs (something you use a lot of in the PC World), computer connection to external hard drives through a USB hub tends to be error-prone if the hub is not powered (connected to house AC power). Unless your keyboard has a power cord, the USB hub on it is not powered. Data transfer to/from HDD is many times faster than to/from a pen or iPod. It's just Physics.

Personally, I connect my Western Digital Essentials USB drive to my MBP USB port and backup nightly error-free.

Pedro,

You never said anything about a second hard disk - Then DON'T reformat!

Unfortunately, the USB port on the keyboard may not supply enough power to support an external hard disk.

"If you have a USB device, or a chain of devices (such as a joystick plugged into a keyboard) that requires more than the available power, use a self-powered USB hub or see if the device comes with a power adapter." [http://docs.info.apple.com/article.html?artnum=58391]

Cheers!

Pedro,

If you have NEW questions, they really should be posted in a new thread.

Nevertheless, in tests I just performed, Time Machine DID NOT attempt to include my iPod that was attached via Firewire. This was despite that fact that the iPod had 'disk use' enabled and yet it did not show up in TM Prefs to exclude.

Please post further questions in a new thread.

Cheers!