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wzzrd
Asked: 2009-06-11 23:46:39 +0800 CST

Filesystem for an external drive that'll only connect to Linux

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I just bought a new 500GB external harddrive. Most of the time I only store operating system ISO's on those things and some movies. Large files anyway, well over 4GiB sometimes, so FAT is out of the question.

So, I'm left wondering. My old external harddrive was NTFS formatted, because it had to be able to connect to Windows boxen sometimes. This new harddrive will not have that requirement. Would NTFS still be the best option? Would one of the ext{2,3,4} filesystems be a good choice for a removable disk? Are there filesystems that I am unaware of that would fit the bill?

"The bill" here would be a stable filesystem that is able to survive an unclean disconnection, is quick, can handle files of over 4GiB and is able to be used on at least kernels 2.6.28 and up.

Update: I hadn't taken xfs into account, and it's large filesystem support is interesting. I'll take a look at the operating systems / kernels I am using (RHEL5, CentOS5, Ubuntu 9.04 and 8.04, Fedora11) to see if those kernels support xfs. I think I remember some of them (the distros) not supporting it by default, but then again, maybe I'm mistaking jfs for xfs here.

The sync option too, is interesting, but that would mean creating UDEV rules for this device on all of my machines, which is not a huge problem, but still something I'll have to keep in mind.

Finally, taken xfs and the sync option, I'm wondering whether the performance gain for xfs and the performance hit with the sync option would be noticeable over the - still rather limited - USB interface.

linux filesystems ext3 xfs ext4

7 Answers

  1. Best Answer

    Personally I use XFS all over the place (and it sound like that's for personal use).

    On an administrational decision it's not that important regarding size, with a 500GB disk you are nowhere near the limits of any filesystem (except FAT as David Schmitt pointed out). Do not consider NTFS, it may have read support but using NTFS under linux is just plain wrong.

    I'd still stay with ext3 is is well tested and has the largst toolset available in case someting happens to your data.

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  2. I'd go with ext3, hands down. I've heard that ext4 isn't that stable yet (don't shoot me if I'm wrong) it's got journalling, so unclean disconnects shouldn't be a problem.

    On ext3, there is always a portion of the disk hidden (5%). This is for when a root drive get's swamped, you can still log in at runlevel 1 to remove some data. On an external hard drive, you can switch this to 1% (to be safe):

    # tune2fs -m 1% /dev/sdb1
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  3. The filesystem is almost irrelevant. You want to mount the filesystem "sync" though. That'll cost you write performance, but you can be sure that all the data is written after the cp is finished.

    Of course, mount -o remount,async is your friend if you want to temporarily get the performance.

    To actually give a specific answer too, I would recommend ext3 with the data=journal and sync mount options.

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  4. Most filesystems won't cope very well with being disconnected without being unmounted first, but you can mitigate that by using a journaled filesystem. Ext3 with data=journal would work, as this journals the data, as well as the metadata. It's a little slower, but safer. XJS and JFS are also journaled filesystems, but I don't know if they do journalling of data as well as metadata.

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  5. I'd use XFS and carefully remember to unmount the disk before unplugging it.

    Edit: Arrf, didn't see the requirement for unclean disconnects. Mount it with "sync" as David Schmitt pointed out. I'd still unmount it before plugging out (when it's possible).

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  6. I use ext3 for my external drives for these reasons:

    1. It's a journaling file system, and will thus better survive disconnections
    2. It's the same filesystem I use for / and /usr and /home (etc...)
    3. I know that it supports all of the extra attributes that I need, for example, for selinux, so when I make a backup all attributes are preserved.

    If you are using selinux or any other system that makes use of extended attributes or ACLs, make sure that your backup media is formatted using a file system that can back up those very same attributes or ACLs.

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  7. If you want something that will tolerate (May not like it) being yanked out is ZFS.

    EDIT ZFS is support on Linux with ZFS ON FUSE

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