Step-by-Step ddrescueview Workflow for Emergency Data RecoveryWhen a drive starts failing — clicking noises, unreadable partitions, or a sudden drop in SMART health — your priority is to preserve as much data as possible with minimal further stress to the media. GNU ddrescue is a powerful command-line tool designed for careful, automated sector-by-sector copying from damaged storage devices. ddrescueview is a graphical front-end that visualizes ddrescue’s mapfile and progress, making it easier to plan and monitor a multi-pass rescue. This guide gives a complete, practical workflow using ddrescue and ddrescueview for emergency data recovery, covering preparation, execution, and post-recovery verification.
1. Before you begin — safety, tools, and mindset
- Work on a copy, not the original: If possible, make an image of the failing drive to work from; but if the drive is very unstable, imaging might stress it further. Decide based on symptoms: if the drive still responds reliably, create an image; if it’s noisy/intermittent, consider working directly but carefully.
- Assemble tools:
- A healthy Linux system (live USB like Ubuntu, SystemRescue, or any distro with ddrescue/ddrescueview installed).
- Sufficient target storage (external drive or large internal drive) for the rescued image and recovered files.
- ddrescue (GNU ddrescue) and ddrescueview installed. On Debian/Ubuntu: sudo apt install gddrescue ddrescueview
- A write-blocker or read-only adapter if available (helps avoid accidental writes).
- Minimize writes to the failing drive: Disable automount, avoid fsck or file manager browsing of the drive, and do not attempt file-level recovery before imaging.
- Document everything: device names, ddrescue commands used, mapfile locations, timestamps. This helps if you need professional help later.
2. Identify devices and prepare targets
- Boot your recovery system and open a terminal.
- List block devices:
lsblk -o NAME,SIZE,FSTYPE,MOUNTPOINT,LABEL sudo fdisk -l - Identify the failing source device (example: /dev/sdb) and a target device or image file location (example: /media/recovery/bigdrive/rescue.img or /dev/sdc).
- Create a directory to store ddrescue mapfiles and logs:
mkdir -p ~/recovery/ddrescue cd ~/recovery/ddrescue
3. First-pass imaging: copy what’s readily readable
Goal: copy all good sectors quickly with minimal retries.
Command pattern:
sudo ddrescue -n -v /dev/sdb /media/recovery/rescue.img rescue.map - -n: no scraping (skip retrying bad sectors)
- -v: verbose
- rescue.map: mapfile tracking progress
Why: This gets the bulk of readable data fast, reducing stress on the drive.
Monitor progress in terminal, but also open ddrescueview and load the mapfile (rescue.map) and image/target. ddrescueview will show green blocks for recovered sectors and red for bad ones.
4. Second-pass: retry problematic areas with controlled parameters
After first pass, target remaining bad areas with limited retries and slower read settings.
Example:
sudo ddrescue -r3 -R -v /dev/sdb /media/recovery/rescue.img rescue.map - -r3: retry bad areas up to 3 times
- -R: reverse direction reads (helps with some drives)
Alternatively, use smaller blocks and timeouts via ddrescue options to avoid long hangs. Adjust -r and -R based on drive behavior.
Use ddrescueview to zoom into red areas and note their positions and sizes. Plan targeted scraping for big contiguous bad regions.
5. Scraping and trimming: aggressive recovery of stubborn sectors
When safe, increase aggression stepwise:
- Increase retries: -r10 or more, but be cautious — long retries can overheat or further damage a drive.
- Use –max-read-rate and –timeout to limit stress.
- Use ddrescue’s –cluster-size (older versions) or –input-position/–output-position to focus on regions.
Example focused scrape:
sudo ddrescue -r10 --max-retries=10 --timeout=10 /dev/sdb /media/recovery/rescue.img rescue.map Watch SMART stats (smartctl) and temperature; stop if errors escalate.
6. Use ddrescueview to prioritize and plan passes
ddrescueview strengths:
- Visual map of recovered, non-recovered, and non-tried areas.
- Zoom and select regions to view offsets and sizes.
- Export lists of bad areas to script targeted ddrescue commands.
Workflow with ddrescueview:
- Open the mapfile and image/device.
- Identify large contiguous red areas — prioritize those containing filesystem metadata (start of partition, superblocks).
- Plan targeted passes: rescue specific offsets with ddrescue’s –input-position/–size options.
- Save updated mapfile after each pass to avoid redoing work.
7. Extracting files from the image
Once imaging reaches a stable state (no more recoverable sectors or you’ve exhausted retries), mount the image read-only or use file-recovery tools.
Mount read-only:
sudo mkdir /mnt/recovery sudo mount -o ro,loop,offset=$((START*512)) /media/recovery/rescue.img /mnt/recovery Calculate START if partition doesn’t begin at 0 (use fdisk -l rescue.img).
File recovery tools:
- photorec for file carving (recovers many file types without filesystem).
- testdisk for filesystem repair/partition recovery.
- scalpel or foremost for carving specific file types.
Note: Carving ignores filenames and directory structure.
8. Post-recovery verification and cleanup
- Verify recovered files open correctly; prioritize irreplaceable files.
- Run checksum comparisons if you had prior hashes.
- Keep rescue.map and logs; they document what was unreadable.
- If critical data is still missing, consider professional lab recovery.
9. Practical tips and cautionary notes
- Work in a cool, ventilated place; failing drives can overheat.
- If the drive emits unusual mechanical noises, consider stopping and consulting a lab.
- Avoid writing to the source drive. Use images and mapfiles to track progress.
- Incremental approach: increase ddrescue aggression slowly.
- If multiple drives are failing, process them one at a time to avoid confusion.
10. Example complete command sequence
# First fast pass sudo ddrescue -n -v /dev/sdb /media/recovery/rescue.img rescue.map # Second pass with retries and reverse reads sudo ddrescue -r3 -R -v /dev/sdb /media/recovery/rescue.img rescue.map # Aggressive targeted scrape (example) sudo ddrescue -r10 --timeout=10 -v /dev/sdb /media/recovery/rescue.img rescue.map This workflow balances speed, safety, and thoroughness: start with a quick first pass to capture healthy sectors, use ddrescueview to analyze and plan targeted retries, and escalate scraping carefully while monitoring the drive’s behavior. Preserve mapfiles and logs — they are invaluable records of what was recoverable and what wasn’t.
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