what format does a usb have to be to be bootable for a mac

What Format Does A Usb Have To Be To Be Bootable For A Mac OS X

Its the closest thing we have to a universal file system format, which is why most flash drives are formatted this way right out of the box.

What Format Does A Usb Have To Be To Be Bootable For A Mac OS X

The first format, FAT32, is fully compatible with Mac OS X, though with some drawbacks that well discuss later.

If the drive comes formatted in NTFS, which is the default file system for Windows, youre going to want to re-format the drive because Mac OS X cant write files to NTFS-formatted volumes (at least not without a bunch of extra work thats beyond the scope of this article).

How do you tell which format your brand-new USB drive has Hook it up to your Mac and launch the Disk Utility app, located in your Utilities folder (which is in Applications).

Your new drive should appear in the left-hand column, and clicking the Partition tab will bring up info on the drive which includes its current format.

If the drives format comes up as MS-DOS (FAT) or, less likely, ExFAT, you may be able to simply leave the drive as-is and not bother reformatting it.

If the drive is listed as NTFS-formatted, youre going to need to format it to something else if you want full compatibility with Mac OS X.

There are several possible file system formats you can use for a USB flash drive, and changing them in Disk Utility is as easy as selecting the number of partitions you want on the drive (usually just one), picking the format you want for the drive, and clicking Apply.

Note that this will erase all information on the drive, so make absolutely sure youve got copies of everything before moving forward.

Disk Utility gives you five different choices for drive formats in OS X Lion.

Unless you have extraordinary needs, you can safely ignore two of them: Mac OS Extended (Case-sensitive, Journaled) and Free Space.

Mac OS Extended (Journaled) - This is the default file system format for Mac OS X drives.

Advantages: Formatting your USB flash drive this way will give you full interoperability with Macs.

It also includes support for features from OS X Lion, such as Versions.

You can even set up an OS X startup drive if you have the right files, the know-how, and a big enough flash drive, which will allow you to boot your Mac off an external disk if something goes wrong with your built-in drive.

The Mac OS Extended (Journaled) option will have the highest degree of support for Mac OS X features, and theres no limit to the size of files you can put on the drive.

Disadvantages: Windows-running PCs can read files from drives formatted this way, but they cant write to them (at least not without the same amount of work it takes to get OS X to write to NTFS-formatted drives).

If youre transferring files from Macs to PCs, this wont be an issue; however, transferring files from PCs to Macs wont be possible if your drive is formatted in Mac OS Extended (Journaled).

If you will only be working with Macs and not PCs, this may not be an issue.

Otherwise, you may need to consider one of the file formats discussed below.

MS-DOS (FAT) - This is Disk Utilitys name for the FAT32 filesystem.

Advantages: FAT32 offers near-universal interoperability with virtually every computing system on the planet.

A drive formatted this way can easily transfer files between Macs and PCs.

You can also move files to video game systems like the PlayStation 3, Xbox 360, and Wii.