Filesystems For Removable Disks?

An anonymous reader asks: "I have recently (as in today ) acquired a 250GB external HD with both USB2 and Firewire ports, with an eye to using it to carry around all my stuff (my humungous e-mail archive, ISO images of whetever distro I'm running, music and work files - I do a lot of database work, so I often need to move 40GB+ database dumps). The thing is, In order to make proper use of it I have to be able to mount and write to it on all three platforms I use: Windows (easy, it comes formatted as FAT32), Linux (trivial mount syntax) and Mac OS X (it just works as is, since it also supports FAT32). However, I'd like to get rid of FAT32." What filesystems, aside from the FAT varieties, have decent support across the major operating systems?

"The disk comes factory-formatted (Windows doesn't allow you to format a disk this big as a single FAT32 partition), and even though I'm not running against any FAT32 limitations yet, I was wondering if there was a better filesystem to use. NTFS would be perfect (given its rock-solid transaction support - always useful on an external drive), but the Linux versions are far from reliable for large file writes and Mac OS X lacks it. ext3 isn't supported on Windows or the Mac (as far as I know).

In short, my requirements are:

• The filesystem must be read/write for Windows, Linux and Mac
• The disk must have a single partition
• There must be tools available for all three OSs to format the HD with that filesystem in case something goes wrong and I'm away from home base

However, if I'm to be stuck with FAT32, I'd appreciate pointers to utilities for reformatting the HD with a single 250GB partition for Mac OS X and Windows (the built-in Disk Manager only lets me format 40GB partitions in FAT32, to force people to move to NTFS)."

Comments

Re:Give it a rest!

[torpor]

Right, exactly. This isn't a 'switch', its a 'compare'.

I myself am very interested in the answer. I wonder if the solution may be to have an ext3 (or xfs, or jffs) shim for Win32, also?

Man, if only there were an *open*, *journaled*, *fast* and *efficient* filesystem which all 3 OS's were allowed to play well with.

Seems to me if the answer to this "Ask Slashdot" ends up being "just use FAT32", then there's an opportunity for a decent OSS project: completely open, cross-platform, fast, journaled filesystem, with code tarballs for all major platforms.

Hmmm...

... followup ...

[torpor]

- Maybe use FAT32, but mount .ISO files?

- Windows is the problem: what open source filesystems are there for Windows, anyway?

How about 2 out of 3? ;)

[Yaztromo]

Okay -- this one is purely for the "FWIW" file...

You could run NT's other original filesystem, HPFS. Linux has decent HPFS support available, the allocation unit is a 512b sector, and it's organized for fast searches and minimal fragmentation. It can also format up to 64GB partitions (although it still has a 2GB filesize limit).

The trick is to get HPFS support for Windows. To do this, you need to get the driver files from Windows NT v3.x (something that, admittedly I'm not sure works with Windows versions > NT 4. I don't do Windows personally, so I haven't tested it -- like I said above, FWIW). That will give you two of the three OSs supported. HPFS has been around for a while, (circa 1988), so you might be able to find something from the Intel FreeBSD world you could port to OS X.

I use HPFS for my 100MB ZIP disks (which I admittedly rarely use anymore for anything than quick archival purposes). It's not journalled, but it uses a bidirectional sector pointer system, so chaining errors are amost always fixable. The big downside is that if the filesystem is dirty, checking it can take a huge amount of time.

It's probably not a practical solution (I didn't and won't claim it is), but it's still a slightly more constructive answer than "Your stuck with FAT32" :).

Yaz.

Re:The question reworded

[Zocalo]

Actually, he *can* reformat the drive as a single FAT32 partition, and use it on all OSes, since he's not running into a physical limitation of FAT32 but rather a deliberate design limitation. "The built-in Disk Manager" bit means he's running NT/XP and IIRC Microsoft has deliberately limited Disk Manager's FAT32 partitions in an effort to encourage people to move to the more advanced NTFS system. Despite this NT/XP is perfectly happy to access FAT32 partitions *much* bigger than 40GB, as long as they are created elsewhere.

I have successfully created FAT32 partitions in excess of 100GB and mounted them under XP using Partition Magic, Linux's *fdisk tools, and Windows 9x. We're talking a removable drive here, so it's not going to be too much hassle to partition the drive on another OS (it's the partitioning that's the problem, not formatting).

A simple process of elimination shows that FAT32 is the most portable filesystem that offers a realistic level of confidence that your OS wont trash the data. It may not be the most sophisticated system out there, but unfortunately that's the price you pay for portability at present. Plus it has the added benefit that it's accessible from a single DOS/Linux boot disk in emergencies - something that's save my ass on numerous occassions.

Re:Windows is your limiting factor

[kasperd]

plus, you can't boot MacOS from ext2

Linux OTOH can boot from almost anything. However I allways boot Linux from ext2. A 31MB /boot partition is more than enough. I don't consider it any problem to have a small boot partition for each OS, even if none of the other OSes can access that partition. Some OSes might even want to (or at least be able to) boot from a partition with no filesystem at all. Linux versions prior to 2.6 could boot from a raw floppy.