The NAS died, or you're migrating away from it, and now you have a bare hard drive and a USB dock. Whether your Mac can read it depends entirely on which NAS wrote it — so before fighting the disk, check which case you're in.
OMV and most hand-built Debian/Ubuntu servers format data drives as a plain ext4
partition. macOS can't read ext4 natively, but with an ext4 driver the disk mounts like
any other volume — read and write. One NAS-specific catch: these systems often enable
ext4 internal quotas, which the open source driver (fuse2fs) refuses to mount.
The error looks like quotas not supported. Omnimount detects this and offers a
one-click fix — it disables the quota feature without touching a single file (your NAS,
if the disk ever goes back, simply rebuilds its quota accounting). This exact case — an OMV
data drive — is verified working end to end.
Synology wraps every volume, even single-disk ones, in Linux software RAID
(mdadm), and SHR adds LVM on top. The filesystem (ext4 or btrfs) lives inside those
layers, so no macOS driver can see it at the partition level — this is a Synology design
decision, not a driver limitation. Your realistic options: connect the drive to a Linux
machine or VM and assemble the array (mdadm --assemble --scan), or use
Synology's own recovery guide. If the volume was btrfs, ext4 tools won't help at all.
What a Mac can still do: clone the whole disk to an
image first, so you work on a copy instead of the only original.
QNAP uses LVM over mdadm. Same verdict as Synology: assemble on Linux, or clone from the Mac and work on the image.
sudo omnimount mount diskXsY --fix-quotaSkip the terminal. Omnimount mounts, checks and clones ext4 and NTFS drives from the menu bar — no kernel extensions, no Recovery Mode, no password prompts. It detects NAS quota disks and fixes them in one click.
Get Omnimount — €9.99 or build it free (GPL)