Image a failing drive on Mac or Windows: a GUI alternative to ddrescue

Why image first

Browsing or repairing a failing drive makes it seek over the same weak areas again and again, and each pass can make it worse. An image saves the healthy data first and leaves the weak spots for later, which is the gentlest way to get the whole drive. After that, all the slow and repeated work happens on the image file, on a healthy disk. See also Recover files from a failing hard drive: image it first.

Is this the right tool for your drive?

An image helps when the drive is logically or mildly physically troubled: it is slow, has a handful of bad sectors, disconnects, or has a damaged file system. It doesn’t help, and can harm, when the fault is mechanical or electrical. Stop and contact a data recovery lab if:

• the drive clicks, ticks, grinds, beeps or repeatedly spins up and down;
• it isn’t detected by the computer’s disk list (diskutil list on Mac, Disk Management on Windows) on any computer;
• it reports a wrong, tiny or zero capacity (a common sign of a failed SSD or controller);
• it has been dropped, wet, burnt or smells burnt;
• it gets very hot or disconnects within seconds of connecting.

Software can’t repair hardware, and further power-ons can scratch platters or lose the one good moment the drive has. Labs can open drives in clean rooms. Ask about their diagnosis fee and a “no recovery, no charge” policy before you send it. Don’t try freezing, tapping or opening the drive.

What you need

• A healthy destination drive with at least as much free space as the failing drive’s size. Empty areas are stored sparsely, so the file is often smaller, but plan for the full size.
• A destination formatted as APFS or exFAT on Mac, NTFS or exFAT on Windows. Avoid FAT32: it can’t hold a single file larger than 4 GB.
• A direct connection: a short, good cable on a port on the computer, not a hub. Keep the computer on mains power and set it not to sleep.

Make the image with Retrova

1. Open Retrova. Choose A drive won’t open, select the failing drive, then choose Copy the whole drive to an image. You can also image a single partition. Retrova asks for administrator rights on both Mac and Windows to read the disk directly.
2. Choose the destination on the healthy drive. Retrova warns you if there isn’t room.
3. Start. Retrova works in steps, and the window shows which one it is on, how much is saved, how much is unreadable and the speed. First it copies all the healthy data and skips ahead when the drive reports errors, so a weak drive isn’t pushed into the bad spots first. Then it trims the edges of the damaged areas, reads what is left sector by sector, and tries the unreadable sectors again (one extra try by default; you can change it). Areas that are all zeros are skipped, which keeps the image file small.
4. Stop or resume whenever you like. Stop keeps everything, including after you close the app. If the drive drops out, reconnect it and resume. Progress is kept in a .map file next to the image, in the same format GNU ddrescue uses, so you can also carry on with ddrescue if you want to keep trying.
5. When it finishes, any unreadable areas are listed in an .unreadable.txt file next to the image. If the image is complete with nothing unreadable, Retrova also saves a SHA-256 fingerprint in a .sha256 file. Open the image file in Retrova as if it were the drive, browse and copy your files, or run Deep scan on it. Then run Verify on the copies.

How this compares with ddrescue

Retrova follows ddrescue’s approach: easy data first, then trim, scrape and retry, with a map file so a job can stop and carry on. Its map is ddrescue-compatible, so the two tools can pick up each other’s work. ddrescue is still the more flexible instrument: it has more options to tune, such as reading backwards, and a long record on badly degraded drives. If you are comfortable in a terminal, that matters; if you want a window, a resume button and a plain log, Retrova covers the same ground. Both read; neither repairs.

After imaging

1. Put the failing drive away. Don’t use it again for anything you care about.
2. Recover from the image. The unreadable-areas list tells you which parts of which files may be damaged: an unreadable area inside a photo means a damaged photo.
3. If the image’s file system is damaged, open it with A drive won’t open, or run Deep scan (72 file types, files stored in one piece, names lost).
4. Verify your recovered files.

What Retrova can’t do: it can’t undelete files with their names on APFS, ext or other file systems (only NTFS, FAT and exFAT), can’t open an encrypted drive without its password or recovery key, can’t open the startup disk of a T2 or Apple silicon Mac away from that Mac, doesn’t handle RAID sets or phones, and can’t fix a drive with physical damage. Retrova’s builds aren’t signed or notarised yet, so macOS and Windows will show a warning the first time you open it.

What not to do

Questions

Related guides

• Recover files from a failing hard drive: image it firstSlow, clicking or disconnecting? Copy the healthy data first, then recover from the image.
• Recover files from an APFS drive that macOS won’t mountFirst Aid failed and the volume stays greyed out? Read the APFS structures directly.
• How to check a copy is perfect: verify files byte for byteCopies fail silently. Check recovered files against the original.
• TestDisk vs PhotoRec vs RetrovaWhich free tool fits which problem.
• Open-source data recovery software comparedFree tools you can read the source of.