Which Linux disks Extent opens, and which it doesn't

By what's on the disk

Extent reads ext2, ext3 and ext4 on a partition of either kind – GPT or MBR – on a disk formatted as a whole without partitions, and in a disk image (.img), such as a Raspberry Pi OS image or a backup of a card. A few kinds of Linux partition it doesn't open yet, such as one marked for /usr; it says so. It writes only ext4 with a journal and extents, because only there does every change go through the journal.

By device

Where each device keeps your files, and whether Extent opens that partition. Where Extent opens an ext4 partition, it writes to it too once writing is unlocked – unless the partition uses a feature Extent can't write yet, which it then names.

How to find out what's on yours

• Connect it with Extent installed. Since version 1.0.2 its window lists every Linux partition it couldn't open, with what it found there: LVM, LUKS, RAID, Btrfs, XFS and so on, or damage.
• On the Mac, without Extent: diskutil list in the Terminal. Linux partitions say Linux in the TYPE column – Linux, Linux Filesystem, Linux_LVM, Linux_RAID. How to read that list.
• On Linux: lsblk -f names the file system of every partition – ext4, crypto_LUKS, LVM2_member, linux_raid_member, btrfs, xfs. For an ext4 disk, sudo dumpe2fs -h /dev/sdX1 lists its features on the “Filesystem features” line.

ext4 features that keep a disk read-only

Extent writes ext4 as current Linux distributions create it, including what today's mke2fs turns on by default – metadata checksums and their seed, 64-bit block numbers, the orphan file – and ext4 without 64-bit block numbers, as on a Raspberry Pi OS card. An ext4 disk with any of these features mounts read-only instead, and Extent names the feature:

A feature newer than Extent knows keeps the disk read-only too – or, where the ext4 rules say software that doesn't know it mustn't touch the disk at all, unmounted, with a note that the disk needs a newer Extent. More about what each feature does is in the ext4, ext3 and ext2 guide.

What opens the rest

• anylinuxfs runs a small Linux in a virtual machine and hands the disk to the Mac as a network share: LVM, LUKS, software RAID, Btrfs, XFS and ZFS. Free and open source, from the Terminal, on Apple silicon.
• Luksmith unlocks LUKS and mounts the ext file system inside.
• xlinuxfs reads and writes XFS and Btrfs as well as ext.
• Linux itself – a virtual machine, or the computer the disk came from – opens everything Linux made.
• Every way to read ext4 on a Mac, side by side: how to read and write ext4 on a Mac.

A Linux partition that isn't on this page? Extent's window says what it found. If it's a kind Extent doesn't open yet, tell us at apps@xfanta.com – it helps decide what comes next.

Frequently asked questions