Creación de imágenes de disco y clonación con el comando dd de Linux

# Create image of entire disk
sudo dd if=/dev/sda of=/backup/disk.img bs=4M status=progress

# Create image of specific partition
sudo dd if=/dev/sda1 of=/backup/part.img bs=4M status=progress

# Create sparse image (skips zero-filled blocks, huge space saver on mostly-empty disks)
sudo dd if=/dev/sda of=/backup/disk.img bs=4M conv=sparse status=progress

# gzip (widely available)
sudo dd if=/dev/sda bs=4M status=progress | gzip > /backup/disk.img.gz

# zstd (better ratio, ~60% faster decompression than pigz, use this)
sudo dd if=/dev/sda bs=4M status=progress | zstd -T0 > /backup/disk.img.zst

# Restore complete disk from image
sudo dd if=/backup/disk.img of=/dev/sda bs=4M status=progress

# Restore from gzip-compressed image
gunzip -c /backup/disk.img.gz | sudo dd of=/dev/sda bs=4M iflag=fullblock conv=fsync status=progress

# Restore from zstd-compressed image
zstdcat /backup/disk.img.zst | sudo dd of=/dev/sda bs=4M iflag=fullblock conv=fsync status=progress

# Restore specific partition
sudo dd if=/backup/part.img of=/dev/sda1 bs=4M iflag=fullblock conv=fsync status=progress

# Clone entire disk
sudo dd if=/dev/sda of=/dev/sdb bs=4M status=progress

# Clone with persistent device names (safer, /dev/sdX can change between boots)
sudo dd if=/dev/disk/by-id/ata-Samsung_SSD_860_EVO_500GB_S3Z9NB0K of=/dev/disk/by-id/ata-WDC_WD10EZEX_WD-WMC1T0123456 bs=4M status=progress

# Verify clone (reads entire disk twice, slow but correct)
sudo cmp /dev/sda /dev/sdb

# Backup MBR (first 512 bytes)
sudo dd if=/dev/sda of=/backup/mbr.img bs=512 count=1

# Restore MBR
sudo dd if=/backup/mbr.img of=/dev/sda bs=512 count=1

# Backup GPT with sgdisk (binary format, includes backup GPT)
sudo sgdisk --backup=/backup/gpt-sda.bin /dev/sda

# Restore GPT to a different disk
sudo sgdisk --load-backup=/backup/gpt-sda.bin /dev/sdb

# Alternative: text dump with sfdisk (human-readable, editable)
sudo sfdisk -d /dev/sda > /backup/sda.parts

# Restore to another disk
sudo sfdisk /dev/sdb < /backup/sda.parts

# Create a snapshot (size the COW area vs. expected write rate during backup)
lvcreate -L 20G -s -n root-snap /dev/vg0/root

# Image the frozen snapshot (not the live volume)
sudo dd if=/dev/vg0/root-snap of=/srv/backups/root-$(date +%F).img bs=4M status=progress

# Clean up the snapshot
lvremove -f /dev/vg0/root-snap

# Freeze the filesystem (blocks all writes)
sudo fsfreeze -f /mnt/data

# Image while frozen
sudo dd if=/dev/sda1 of=/srv/backups/data-$(date +%F).img bs=4M status=progress

# Unfreeze immediately after dd finishes
sudo fsfreeze -u /mnt/data

# Create bootable USB from Linux ISO
sudo dd if=/path/to/linux.iso of=/dev/sdX bs=4M status=progress && sync

# Ventoy — install once, then just copy ISOs to the USB stick
sudo ventoy -i /dev/sdX
# Then copy any ISOs: cp /path/to/Win11.iso /dev/sdX1/

# WoeUSB — creates a proper Windows bootable USB
sudo woeusb --target-filesystem NTFS --device /path/to/Win11.iso /dev/sdX

# Rufus (from Windows or another OS) also works well

# Full-image hash comparison (correct but slow — reads entire disk)
sha256sum /path/to/linux.iso
sudo dd if=/dev/sdX bs=4M status=progress | sha256sum

# Or use bmaptool which verifies SHA256 while flashing (see alternatives section)
bmaptool create disk.img -o disk.img.bmap
sudo bmaptool copy /backup/disk.img.gz /dev/sdX

# Single-pass zero fill (NIST "Clear" — sufficient for modern HDDs)
sudo dd if=/dev/zero of=/dev/sda bs=4M status=progress conv=fsync

# Verify
sudo hexdump -C /dev/sda | head -20

# SATA SSD — secure discard
sudo blkdiscard -s /dev/sda

# NVMe — user data erase
sudo nvme format --ses=1 /dev/nvme0n1

# ATA Secure Erase (SATA drives)
sudo hdparm --user-master u --security-set-pass p /dev/sdX
sudo hdparm --security-erase p /dev/sdX

# Destroy all key slots — data is permanently inaccessible
sudo cryptsetup luksErase /dev/sda2

# conv=sparse — skip zero-filled blocks on output (saves space on mostly-empty disks)
sudo dd if=/dev/sda of=/backup/disk.img bs=4M conv=sparse status=progress
# Do NOT use conv=sparse when restoring to a device

# iflag=fullblock — fill incomplete reads to full block size (critical for pipes)
# Used automatically when reading from pipes with count=
gunzip -c /backup/disk.img.gz | sudo dd of=/dev/sdb bs=4M iflag=fullblock

# conv=fsync — fsync output before dd exits (ensures data hits physical disk)
sudo dd if=/backup/disk.img of=/dev/sda bs=4M conv=fsync status=progress

# oflag=direct — bypass page cache (useful for benchmarking and raw device writes)
dd if=/dev/zero of=/tmp/benchmark bs=4M count=1024 oflag=direct

# oflag=nocache — drop page cache after writing (coreutils 9.7+ improved detection)
sudo dd if=/dev/sda of=/backup/disk.img bs=4M oflag=nocache status=progress

# Compressed image on-the-fly with zstd
sudo dd if=/dev/sda bs=4M status=progress | zstd -T0 > /backup/disk.img.zst

# Compressed image on-the-fly with gzip
sudo dd if=/dev/sda bs=4M status=progress | gzip -c > /backup/disk.img.gz

# Network transfer with compression
sudo dd if=/dev/sda bs=4M status=progress | zstd -T0 | ssh user@remote 'cat > /backup/remote.img.zst'

# With progress monitoring via pv (pipe viewer v1.11.0)
sudo dd if=/dev/sda bs=4M | pv -s $(sudo blockdev --getsize64 /dev/sda) | zstd -T0 > /backup/disk.img.zst

# Continue copying despite read errors
sudo dd conv=noerror,sync iflag=fullblock if=/dev/sda1 of=/backup/rescue.img

# Use ddrescue for better error handling (almost always the right choice for failing drives)
sudo ddrescue -d -r3 /dev/sda /backup/image.img /backup/rescue.log

# Create file with random data for testing
dd if=/dev/urandom of=/tmp/test-1gb.dat bs=1M count=1024

# Create file with zeros (faster, compressible)
dd if=/dev/zero of=/tmp/test-1gb-zeros.dat bs=1M count=1024

# Create sparse file (doesn't use actual disk space)
dd if=/dev/zero of=/tmp/sparse.dat bs=1M count=1024 seek=1024

# Benchmark disk write speed
dd if=/dev/zero of=/tmp/benchmark bs=1M count=1024 oflag=direct
rm /tmp/benchmark

# status=progress shows throughput and bytes transferred
sudo dd if=/dev/sda of=/backup/image.img bs=4M status=progress

# Manual signal for progress (background dd)
sudo dd if=/dev/sda of=/backup/image.img bs=4M &
# In another terminal:
sudo kill -USR1 $(pidof dd)

# Continuous monitoring with watch
watch -n 1 'sudo kill -USR1 $(pidof dd) 2>/dev/null'

# Using pv (pipe viewer) for better progress display
sudo dd if=/dev/sda bs=4M | pv -s $(sudo blockdev --getsize64 /dev/sda) | dd of=/backup/image.img bs=4M

# Monitor disk I/O during operation
iostat -x 1 /dev/sda

remaining_time = (total_bytes - bytes_transferred) / current_speed

# Check drive health
sudo smartctl -a /dev/sda

# Error-tolerant copying with dd
sudo dd if=/dev/sda of=/backup/image.img bs=4M conv=noerror,sync iflag=fullblock status=progress

# Better error recovery with ddrescue (1.30)
sudo ddrescue -d -r3 /dev/sda /backup/image.img /backup/rescue.log

# Check if device is mounted
lsblk | grep sda
mount | grep sda

# Unmount if necessary
sudo umount /dev/sda1

# Ensure proper permissions (usually requires root)
sudo dd if=/dev/sda of=/backup/image.img bs=4M status=progress

dd --version
# If it shows uutils, install GNU coreutils:
sudo apt install coreutils

# Basic rescue operation
sudo ddrescue -d -r3 /dev/sda /backup/image.img /backup/rescue.log

# New in ddrescue 1.29.1: treat known garbage as read errors
# (for drives that return fake data instead of erroring)
sudo ddrescue --bad-sector-data=/tmp/garbage.bin /dev/sda /backup/image.img /backup/rescue.log

# New in ddrescue 1.30: dead-head recovery is orders of magnitude better
# (283 errors vs 3,782,794 in testing with a 4-head drive and one dead head)
# Also: --no-sweep, --size=output for --force overwrite, underscore numbers in args
sudo ddrescue -d -r3 --no-sweep /dev/sda /backup/image.img /backup/rescue.log

# Create a block map from your image
bmaptool create disk.img -o disk.img.bmap

# Flash with verification (refuses to write to mounted devices)
sudo bmaptool copy /backup/disk.img.gz /dev/sdX

#!/bin/bash
# lvm-snapshot-backup.sh — consistent backup via LVM snapshot
DATE=$(date +%Y%m%d_%H%M%S)
BACKUP_DIR="/srv/backups/disk-images"
LOG_FILE="/var/log/disk-backup.log"
SNAP_SIZE="20G"
SNAP_NAME="root-snap"

mkdir -p "$BACKUP_DIR"

echo "$(date): Creating LVM snapshot" >> "$LOG_FILE"
lvcreate -L "$SNAP_SIZE" -s -n "$SNAP_NAME" /dev/vg0/root >> "$LOG_FILE" 2>&1

if [ $? -eq 0 ]; then
    echo "$(date): Starting snapshot backup" >> "$LOG_FILE"
    sudo dd if="/dev/vg0/$SNAP_NAME" of="$BACKUP_DIR/system-backup-$DATE.img" bs=4M iflag=fullblock conv=fsync status=progress 2>> "$LOG_FILE"

    if [ $? -eq 0 ]; then
        echo "$(date): Backup completed, compressing with zstd" >> "$LOG_FILE"
        zstd --rm "$BACKUP_DIR/system-backup-$DATE.img"
    else
        echo "$(date): Backup failed!" >> "$LOG_FILE"
    fi

    # Clean up snapshot
    lvremove -f "/dev/vg0/$SNAP_NAME" >> "$LOG_FILE" 2>&1

    # Retention: keep 7 days of compressed backups
    find "$BACKUP_DIR" -name "*.img.zst" -mtime +7 -delete
else
    echo "$(date): Snapshot creation failed!" >> "$LOG_FILE"
    exit 1
fi

# Emergency system restore from image
sudo dd if=/backup/system-backup.img of=/dev/sda bs=4M iflag=fullblock conv=fsync status=progress

# Restore from network (zstd-compressed)
ssh backup-server 'cat /backup/system.img.zst' | zstdcat | sudo dd of=/dev/sda bs=4M iflag=fullblock conv=fsync status=progress

# Quick MBR repair from backup
sudo dd if=/backup/mbr.img of=/dev/sda bs=512 count=1

# GPT repair from backup
sudo sgdisk --load-backup=/backup/gpt-sda.bin /dev/sda

# Create base image for VM templates
sudo dd if=/dev/sda of=/vm-images/template.img bs=4M status=progress

# Compress for storage
zstd /vm-images/template.img