Synology Hybrid RAID (SHR) is essentially an abstraction layer built on standard Linux storage technologies. What makes it unique is its dynamic volume management that:

• Automatically optimizes disk space utilization across mixed-size drives
• Creates optimal RAID configurations (RAID1/5/6) based on disk count
• Simplifies volume expansion without manual intervention

The magic happens through this stack:

Physical Disks → Linux MD RAID (mdadm) → LVM2 → Filesystem

Key implementation details:

• Uses mdadm for RAID array creation
• LVM handles dynamic volume management
• Custom scripts automate the pairing process

Here's how to replicate SHR functionality manually:

1. Disk Preparation

# Identify disks
lsblk -o NAME,SIZE,ROTA

# Partition disks (GPT recommended)
parted /dev/sdX --script mklabel gpt
parted /dev/sdX --script mkpart primary 0% 100%
parted /dev/sdX --script set 1 raid on

2. RAID Array Creation

For a 2-disk setup (RAID1 equivalent):

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdX1 /dev/sdY1

For 3+ disks (RAID5 equivalent):

mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/sdX1 /dev/sdY1 /dev/sdZ1

3. LVM Configuration

# Create physical volume
pvcreate /dev/md0

# Create volume group
vgcreate vg_data /dev/md0

# Create logical volume
lvcreate -l 100%FREE -n lv_storage vg_data

# Format filesystem
mkfs.ext4 /dev/vg_data/lv_storage

Adding a new disk to existing array:

# Add new partition to RAID
mdadm --add /dev/md0 /dev/sdW1

# Grow RAID array
mdadm --grow /dev/md0 --raid-devices=4

# Extend physical volume
pvresize /dev/md0

# Extend logical volume
lvextend -l +100%FREE /dev/vg_data/lv_storage

# Resize filesystem
resize2fs /dev/vg_data/lv_storage

Here's a simplified bash script to automate SHR-like behavior:

#!/bin/bash
# SHR-like auto RAID/LVM setup
disks=($(ls /dev/sd[b-z]1 2>/dev/null))

if [ ${#disks[@]} -lt 1 ]; then
    echo "No suitable disks found"
    exit 1
fi

raid_level=1
[ ${#disks[@]} -ge 3 ] && raid_level=5
[ ${#disks[@]} -ge 5 ] && raid_level=6

mdadm --create /dev/md0 --level=$raid_level --raid-devices=${#disks[@]} ${disks[@]}
pvcreate /dev/md0
vgcreate vg_data /dev/md0
lvcreate -l 100%FREE -n lv_storage vg_data
mkfs.ext4 /dev/vg_data/lv_storage
mkdir -p /mnt/storage
mount /dev/vg_data/lv_storage /mnt/storage

Essential commands for ongoing management:

# Check RAID status
mdadm --detail /dev/md0

# Monitor rebuild progress
cat /proc/mdstat

# Check LVM status
vgdisplay
lvdisplay

• Always maintain backups - RAID is not a backup solution
• Monitor disk SMART status regularly
• Consider using ZFS as alternative for more advanced features
• Test recovery procedures before deployment

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Synology Hybrid RAID (SHR) is essentially a smart abstraction layer built on standard Linux tools like LVM and mdadm. The key advantage is its ability to:

• Automatically optimize storage allocation across disks of different sizes
• Support single-disk redundancy (similar to RAID 5) or double-disk redundancy (RAID 6)
• Simplify storage expansion without requiring identical disk sizes

To replicate this functionality on a standard Linux system, we'll need:

# Install required packages on Debian/Ubuntu
sudo apt-get install lvm2 mdadm

# For RHEL/CentOS
sudo yum install lvm2 mdadm

Here's how to create a flexible storage pool with similar characteristics to SHR:

1. Preparing Disks

First, identify your disks and wipe any existing filesystems:

lsblk  # List available disks
sudo wipefs -a /dev/sdX  # Repeat for each disk

2. Creating RAID Arrays

Use mdadm to create flexible arrays:

# For disks of different sizes (example with 3 disks)
sudo mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/sdb /dev/sdc /dev/sdd

3. LVM Configuration

Set up LVM on top of the RAID array:

sudo pvcreate /dev/md0
sudo vgcreate vg_storage /dev/md0
sudo lvcreate -n lv_data -l 100%FREE vg_storage
sudo mkfs.ext4 /dev/vg_storage/lv_data

To simulate SHR's automatic expansion capability, create this script (save as expand_storage.sh):

#!/bin/bash
NEW_DISK=$1

# Add new disk to RAID
sudo mdadm --add /dev/md0 $NEW_DISK
sudo mdadm --grow /dev/md0 --raid-devices=$(( $(lsblk -l | grep -c "md0") + 1 ))

# Resize LVM
sudo pvresize /dev/md0
sudo lvextend -l +100%FREE /dev/vg_storage/lv_data
sudo resize2fs /dev/vg_storage/lv_data

Essential commands for managing your setup:

# Check RAID status
cat /proc/mdstat
sudo mdadm --detail /dev/md0

# Check LVM status
sudo vgdisplay
sudo lvdisplay

For optimal performance with mixed disk sizes:

• Place larger disks at the beginning of your RAID array
• Consider using --write-mostly flag for slower disks
• Adjust chunk size based on workload (e.g., --chunk=512K for large files)