Apple Event: May 7th at 7 am PT
I have a LaCie 250 GB harddrive that had been used with a Windows computer and is formatted for MS-DOS (FAT). Is there a way to reformat it so it can be read and written by OSX?
Powerbook G4, Mac OS X (10.3.7)
Yes. Use Disk Utility. Set it to erase using the "Mac OSX Extended Journaled" filesystem. In Disk Utility "Erase" means format.
Edward Redish wrote:
I have a LaCie 250 GB harddrive that had been used with a Windows computer and is formatted for MS-DOS (FAT).
It's very likely FAT32. Out of the box, Mac OS X can read and write FAT16 and FAT32, but it can only read NTFS. So you can use it as it is, unless you plan to use it exclusively with Mac OS X.
Is there a way to reformat it so it can be read and written by OSX?
Yes. It's called Disk Utility and it lives in your </Applications/Utilities> folder. If you plan to use this drive exclusively with Mac OS X, use Disk Utility and format it as HFS+, which is the default. If you plan to use it also with PCs or other devices (eg, media player), your best bet is to leave it as FAT32.
Along with Steve's note. When you're in Disk Utility, make sure to change the partition map to GUID. Coming from Windows, it will be Master Boot Record. You can leave it that way if all you're going to use it for is data, but newer Macs require it to be GUID if you want to be able to boot your Mac to that drive.
Kurt, could you please elaborate on your advice? Can Macs even boot from a FAT32 volume? Can one choose the partition map in Disk Utility? I cannot find this option. Just like choosing between FAT16 and FAT32, it seems to me that the GUI version (by contrast with the CLI version) does not leave this to the latitude of the user.
I think that, unless one is comfortable with diskutil (and it doesn't seem to me that the OP is), one needs to understand the distinction between disk and volume. If one reformats the disk and chooses HFS+ in Disk Utility, it will automatically use GPT, so a less experienced user doesn't need to worry about partition maps.
Can Macs even boot from a FAT32 volume?
No. The drive's file format must be HFS+. The partition map is separate from the file format.
Can one choose the partition map in Disk Utility? I cannot find this option.
Yes. You can go through the steps to see how it's done. Just don't hit Apply, or you'll wipe out the drive. You can't do this test on the startup drive, so choose an external or other physical drive.
Open Disk Utility and click on the physical drive icon at the left, not one of the logical drive names. Such as shown next.
After selecting a physical drive, you'll have the Partition tab at the right. Click on that heading. Notice below the graphic for the Volume Scheme, that Options is grayed out. Change the pulldown for the scheme from Current to anything else. Even just one partition again. The Options button will now be enabled. Click that to show the partition map options.
While some fairly recent Macs will still boot to a drive set as Apple Partition Map, Apple strongly recommends against using it. It's being phased out in favor of GUID. The latest Macs are unlikely to boot to a drive set to use Apple Partition Map. When trying to install OS X to such a drive, it will even tell you it can't be installed on the chosen drive. Click Cancel and then close Disk Utility. It will tell you there are unsaved changes. Click Quit so nothing is applied.
If one reformats the disk and chooses HFS+ in Disk Utility, it will automatically use GPT, so a less experienced user doesn't need to worry about partition maps.
No, it won't. The partition map will not change no matter how many times your format a drive. You must set the proper partition map manually. So in this case, the user must use Disk Utility to first change the partition map from Master Boot Record to GUID, if they plan on using it as a bootable OS X drive. Even if not, it's still very much recommended to change it to GUID.
Kurt Lang wrote:
Can Macs even boot from a FAT32 volume?No. The drive's file format must be HFS+.
Thank you. There was a certain rhetorical aspect to that question.
You can go through the steps to see how it's done
Thank you. I tend to use the CLI version, and I didn't know one could change the partition map with the GUI version. It's good to know that.
No, it won't. The partition map will not change no matter how many times your format a drive.
I'm sorry, but that is incorrect. I've just tested it repeatedly in Disk Utility (the GUI version) -- if I choose format as JHFS+, the partition map is automatically changed to GUID. This is pretty much what I expected; moreover, if I choose FAT, it is automatically changed to MBR. It makes sense, because a GPT FAT volume won't be useable on Windows -- not easily, at least. It's in diskutil, the CLI version, that partition map type has to be specified separately from file system; which, again, makes sense.
I've just tested it repeatedly in Disk Utility (the GUI version) -- if I choose format as JHFS+, the partition map is automatically changed to GUID.
Now that is interesting. Disk Utility never used to do that. Shows how long it's been since I last set up a new drive. 😉 Good information to know. Thanks!
Disk Utility just reformatted an MBR partitioned (FAT32) HD for me to HFS+ and DID NOT change the MBR partitioning. I had to do the change to GUID manually. Running 10.6.8 on an i7 Mac. I guess YMMV.
Frank
Disk Utility just reformatted an MBR partitioned (FAT32) HD for me to HFS+ and DID NOT change the MBR partitioning.
Now I'm confused, as that's what I expect DU to do. Hmmm.
Me too. Kurt. I've never seen DU spontaneously change the partition map.
Frank Miller2 wrote:
Disk Utility just reformatted an MBR partitioned (FAT32) HD for me to HFS+ and DID NOT change the MBR partitioning.
You did select the drive, not a volume on the drive, as in Kurt's pic, right? In that case it would be useful to know when DU does changes the partition map. I tested v11.5.2 (298.4) on two SanDisk Cruzers, 4GB and 8GB. What drive did you use?
Yes, I selected the drive. I've been doing this for a long time, and I have never seen DU change the partition map when reformatting - only when manually re-partitioning.
In that case,
I can't speak about past behaviour, because, as a rule, I'm using diskutil; but, FWIW, the behaviour I see is exactly what I should expect.
This may be relevant. Apple KB article HT2434 states:
"On some Intel-based Macs, the Options button does not appear under the partition tab. Use the erase tab to erase the disk instead. This will change the partition scheme to the default 'GUID Partition Scheme.'"
This could possibly account for the differences we've seen.
That would certainly explain it. So is your Mac a very recent model? Just curious, since Apple doesn't say (just "some Intel-based Macs"). I'm wondering if this is how all future Macs will behave.
Nothing wrong with it if they do. GUID is required to install OS X and be able to boot to a drive in the later and latest versions of OS X, and you can still have FAT16, FAT32 and NTFS partitions on a drive with a GUID partition map.
Can I reformat an MS-DOS harddrive for OSX?
