What to do right now
- Do not accept when Windows offers to format or initialise the disk.
- Connect the disk to the PC over SATA or a USB dock, and note the NAS bay order first.
- Use a tool that opens ext4 read-only and copy the files to another disk.
Step by step
Note the bay order and remove the disk
Switch off the NAS and write down which bay each disk was in before removing it. You may need that order if the disks go into a new NAS later.
Connect it to the PC
Use a desktop SATA port or a USB docking station. If Disk Management shows the disk without a drive letter and asks you to initialise it, click cancel.
Select the disk in FileFix Ultimate
Run it as administrator and pick the physical disk. From version 1.0.4 it finds ext2, ext3 and ext4 volumes on the disk and shows their folder structure read-only.
Choose the folders you need
Browse the shared folder structure and pick the folders you need. File names and folders appear as they were.
Copy to another disk
Choose another disk formatted as NTFS or exFAT as the destination. Nothing is written to the NAS disk.
Setups that work and setups that do not
The best chance is a volume that lived on a single disk, or RAID 1 (mirror), where one disk holds the whole ext4 volume. NAS devices often wrap volumes in a management layer such as software RAID or LVM; if the ext4 volume can be found inside that layer, it can be read.
With RAID 5 or 6, or SHR across several disks, the data is split over multiple disks and one disk alone cannot be read. Btrfs, the default on recent Synology models, encrypted shared folders and ZFS are not supported either. In those cases, put all disks in order into a NAS with the same setup, or contact a recovery lab.
What about deleted files?
When ext4 deletes a file, it erases the information about where the file's data was. Files deleted on a NAS are therefore hard to restore with names and folders, and signature search, which finds photos and documents by content, is the realistic option. If the NAS recycle bin was turned on, check that folder first.
When it will not work
- The data is split across several disks, as with RAID 5, RAID 6 or multi-disk SHR.
- The volume uses Btrfs or ZFS, or is encrypted.
- The disk clicks or keeps disconnecting, which is a physical fault.
- Files deleted on ext4 are hard to restore with names and folders.
How FileFix Ultimate helps
- From version 1.0.4, opens ext2, ext3 and ext4 volumes read-only to copy files and folders.
- Never writes to the NAS disk.
- SMART health shows first whether the disk is still safe to read.
- A disk with bad sectors can be imaged first and the files copied from the image.
FileFix Ultimate is free, works offline and never writes to the drive you are recovering from. Check the signature before you run it.
Frequently asked questions
Can Windows read a Synology disk?
Not on its own. You need a tool that reads ext4, and the volume must be complete on that one disk. Btrfs volumes are not supported.
Windows asks me to initialise the NAS disk.
Do not do it. Initialising changes the partition information and makes recovery harder. Cancel and open the disk with a tool that reads ext4.
Can I copy files from one disk of a RAID 5 NAS?
No. The data is split across several disks, so one is not enough. Consider putting all disks in order into a NAS with the same setup.