Drop partition to share between OSes

[Jedis]

I am trying to figure out the best way to go about doing this.

 

I have a triple boot setup with Chameleon acting as the bootloader for Windows 7, Snow Leopard 10.6.3, and Ubuntu 10.10.

 

Win7 can't see any of the 'linux' partitions (I knew this before starting). SL can see the Windows partition and it is mounted, but because Win7 needs NTFS, SL cannot write to the partition. SL also cannot see the Ubuntu partition. When in Ubuntu, it can see the OSX partitions, but not the Win7 partition (I did not try and read/write anything to the SL partition while in Ubuntu so am unsure what does/doesn't work).

 

Is there an easy way to make a universal partition that every OS can read/write to for data? If so, would file system would I use, FAT32? Would splitting an existing partition to make a new one mess up Chameleon and cause boot loader issues?

 

Any suggestions would be greatly appreciated, thanks!

[mulcyber]

Is there an easy way to make a universal partition that every OS can read/write to for data? If so, would file system would I use, FAT32? Would splitting an existing partition to make a new one mess up Chameleon and cause boot loader issues?

 

Any suggestions would be greatly appreciated, thanks!

 

I also triple boot and with two hard drives. I use a 2TB portable USB drive ($70) that all three OS can read and write to, formatted as NTFS. Fat32 cannot have individual files larger than 4GB. The USB is automatically mounted by all 3 OS.

[enochpc]

I also triple boot and with two hard drives. I use a 2TB portable USB drive ($70) that all three OS can read and write to, formatted as NTFS. Fat32 cannot have individual files larger than 4GB. The USB is automatically mounted by all 3 OS.

 

Another option is Dropbox, it's free for 2gb and automatically copies anything saved in selected folders. It also has versions for all three OS's.

[Jedis]

I also triple boot and with two hard drives. I use a 2TB portable USB drive ($70) that all three OS can read and write to, formatted as NTFS. Fat32 cannot have individual files larger than 4GB. The USB is automatically mounted by all 3 OS.

What can I do to get OSX to be able to write to the Windows NTFS partition?

[srs5694]

There are at least three NTFS writing options in OS X 10.6:

 

• Enable built-in read/write support -- This support is reported to be very flaky, so I don't recommend you try it, although it's free. (IIRC, you just need to create an /etc/fstab entry for the partition you want to access, should you be reckless enough to try it.)
  
• Paragon NTFS -- This is a commercial product. I'm not sure how well it works, since I've never used it myself and I've seen relatively few posts about it.
  
• NTFS-3g for OS X -- There are commercial and open source variants of this one. I used the open source version for a while with OS X 10.5 and it seemed fine. I've seen conflicting reports of whether they operate in 64-bit mode in OS X 10.6, though, and I no longer use it since I no longer need it.
  

 

Personally, I wouldn't recommend using any of these tools on your Windows boot partition (C: in Windows). There are two reasons for this. First, OS X doesn't understand Windows' security features. This makes it too easy to accidentally delete or damage critical Windows files, which would be protected by Windows' security features if you were booted into Windows. Second, I'm skeptical that any of these tools is as reliable as Microsoft's own NTFS drivers. (In fact, the built-in read/write support is known to be unreliable, as noted above.) If the driver you use under OS X is less reliable than the Windows driver, that means you'll be exposing yourself to the risk of filesystem damage whenever you use it. These same comments apply to accessing the Windows boot partition from Linux, and to one extent or another to accessing any OS's boot partition from any other OS. (Linux and OS X at least use similar security models, so the first problem is less of an issue for accessing OS X from Linux or vice-versa, given appropriate drivers.)

 

Instead of accessing the Windows boot partition from OS X or Linux, I recommend you create a separate data-transfer/shared-data partition. That way, you can't trash system files, and if the filesystem driver damages the filesystem, you at least won't impair the ability of any OS to boot. If the 4 GiB limit of files in FAT32 isn't a problem, FAT is the best choice for this purpose, since it's well-supported in most or all modern OSes. If the 4 GiB limit is a problem, then NTFS may be the best choice, using the Paragon or NTFS-3g drivers. (In this case, you may need to create an /etc/fstab entry to ensure that the Windows boot partition is not mounted by default.) Unjournaled HFS+ might also be an option; Linux has decent HFS+ drivers (but they permit writes only if the journal is disabled), and there are commercial HFS+ drivers available for Windows.

 

As to the risks of repartitioning, it's hard to say. If your disk uses a hybrid MBR, you'll have to be careful that your adjusted partition table includes the correct partitions, which should include the shared-data partition. If you're on a straight MBR-only system, the risks will be less, but I can't promise that Chameleon won't get confused. You can reduce the risks by placing the new shared-data partition after the OS X partition; that should minimize the risk that critical Chameleon files will be moved or that the partition number for the partition that holds Chameleon will change. In a worst-case scenario, you could boot with a suitable emergency disk and re-install Chamleon. If you don't have such a disk, prepare one and test it ahead of time.