SHR vs RAID 5: Which Should You Use on Your Synology NAS?

When setting up a Synology NAS, one of the first decisions you’ll face is choosing between SHR (Synology Hybrid RAID) and traditional RAID 5. Both provide single-drive fault tolerance, but they work very differently under the hood — and those differences matter for flexibility, upgrades, and long-term use.

This comprehensive comparison covers everything you need to make the right choice: how each works, performance differences, capacity calculations, upgrade paths, and specific recommendations based on your use case.

Understanding SHR (Synology Hybrid RAID)

SHR is Synology’s proprietary RAID system built on top of Linux’s mdraid and LVM technologies. It was designed to solve the biggest pain point of traditional RAID: the requirement for identical drive sizes.

How SHR Works

SHR intelligently partitions drives to maximize usable capacity when mixing different sizes:

1. Divides each drive into partitions matching the smallest drive
2. Creates RAID 5 arrays from matching partitions across drives
3. Uses leftover space on larger drives for additional redundancy or capacity
4. Manages everything automatically — no manual configuration needed

SHR Example with Mixed Drives

Consider a 4-bay NAS with: 4TB + 4TB + 8TB + 8TB drives

With traditional RAID 5: All drives treated as 4TB (smallest size). Usable capacity = 12TB. You’d waste 8TB of the larger drives.

With SHR:

• First 4TB partition from each drive → RAID 5 array (12TB usable)
• Remaining 4TB from the two 8TB drives → RAID 1 mirror (4TB usable)
• Total usable: 16TB vs 12TB with RAID 5

SHR recovers 4TB that RAID 5 would waste — a 33% improvement in this scenario.

SHR Variants

• SHR (SHR-1): Single-drive fault tolerance (equivalent to RAID 5)
• SHR-2: Two-drive fault tolerance (equivalent to RAID 6)

Understanding RAID 5

RAID 5 is the industry-standard redundancy solution, supported by virtually every NAS, server, and storage controller. It distributes data and parity across all drives.

How RAID 5 Works

1. Stripes data across all drives for performance
2. Calculates parity data and distributes it across drives
3. Can reconstruct any single failed drive from parity
4. Requires minimum 3 drives
5. Usable capacity = (N-1) × smallest drive size

RAID 5 Capacity Calculation

SHR vs RAID 5: Direct Comparison

Capacity Comparison: Real-World Scenarios

Scenario 1: Identical Drives

4× 8TB drives in a 4-bay NAS:

• SHR: 24TB usable
• RAID 5: 24TB usable
• Winner: Tie — identical capacity with matching drives

Scenario 2: Mixed Drives (Common Home Setup)

4TB + 4TB + 8TB + 8TB in a 4-bay NAS:

• SHR: 16TB usable
• RAID 5: 12TB usable (treats all as 4TB)
• Winner: SHR — 33% more capacity

Scenario 3: Gradual Upgrade Path

Starting with 4× 4TB, upgrading to 4× 12TB one drive at a time:

With SHR:

• Start: 4× 4TB = 12TB usable
• Replace drive 1 with 12TB, rebuild → still 12TB (one 12TB in the pool)
• Replace drive 2 with 12TB, rebuild → 16TB usable (two 12TB drives can use extra space)
• Replace drive 3 with 12TB, rebuild → 24TB usable
• Replace drive 4 with 12TB, rebuild → 36TB usable

With RAID 5:

• Start: 4× 4TB = 12TB usable
• Replace drives 1-3 with 12TB → still 12TB (smallest drive limits all)
• Replace drive 4 with 12TB, rebuild → 36TB usable (finally!)

Winner: SHR — capacity increases gradually as you upgrade; RAID 5 only increases after ALL drives are upgraded.

Performance Comparison

Sequential Read/Write

For large file transfers (video editing, backups):

• SHR: Comparable to RAID 5
• RAID 5: Industry baseline
• Difference: Negligible (within 5%)

Random Read/Write

For databases, VMs, and small file operations:

• SHR: Slightly more overhead due to LVM layer
• RAID 5: Marginally faster in some benchmarks
• Difference: Typically under 10% — not noticeable in real use

Rebuild Performance

When replacing a failed drive:

• SHR: May rebuild multiple RAID arrays sequentially
• RAID 5: Single array rebuild
• Difference: SHR can take slightly longer with mixed drives, but both depend primarily on drive size and NAS activity

Real-World Performance Verdict

For 99% of home and small business users, performance differences are imperceptible. Both are limited by:

• Network speed (1GbE caps at ~115 MB/s)
• Drive speed (HDDs max ~200 MB/s sequential)
• NAS CPU (not RAID overhead)

Don’t choose based on performance — choose based on flexibility.

The Upgrade Advantage: Why SHR Wins for Most Users

The single biggest advantage of SHR is the upgrade path. Here’s a realistic home user scenario:

Year 1: Initial Setup

You buy a DS923+ with 4× 4TB drives (16TB raw, 12TB usable with SHR/RAID 5).

Year 3: Running Low on Space

You find a good deal on 12TB drives.

With SHR:

• Buy ONE 12TB drive ($200)
• Replace one 4TB drive, rebuild
• Repeat when budget allows
• Capacity grows with each upgrade

With RAID 5:

• Must buy FOUR 12TB drives at once ($800)
• Or accept wasted capacity until all drives are upgraded
• More expensive, less flexible

When to Choose RAID 5 Over SHR

Despite SHR’s advantages, RAID 5 is the better choice in specific situations:

1. Cross-Platform Compatibility

If you might move drives to a non-Synology NAS (QNAP, TrueNAS, etc.), RAID 5 is universally supported. SHR arrays can only be read by Synology devices.

2. Enterprise/Business Requirements

Some organizations require industry-standard RAID for compliance or IT policy reasons. SHR is proprietary.

3. Synology xs+ Models

Enterprise Synology models (DS1823xs+, RS series) don’t support SHR — they’re designed for environments where traditional RAID is expected.

4. All Identical Drives, No Upgrades Planned

If you’re using identical drives and never plan to upgrade (enterprise with lifecycle policies), RAID 5 works identically to SHR with marginally simpler architecture.

5. Maximum Simplicity/Predictability

RAID 5 is well-documented with decades of troubleshooting knowledge. SHR is Synology-specific, though it’s also mature and well-supported.

SHR-2 vs RAID 6: Two-Drive Fault Tolerance

For larger arrays (6+ drives) or large drives (12TB+), two-drive fault tolerance is recommended:

When to use 2-drive fault tolerance:

• Arrays with 6+ drives
• Drives larger than 10TB (long rebuild times)
• Mission-critical data
• Cannot afford downtime during rebuilds

Minimum Drive Requirements

Note: SHR with 2 drives automatically operates as RAID 1 (mirroring). With 3+ drives, it operates similarly to RAID 5.

Migration: Can You Switch Between SHR and RAID 5?

Short answer: No, not without data loss.

You cannot convert an existing SHR array to RAID 5 or vice versa. To switch, you must:

1. Back up all data externally
2. Delete the storage pool
3. Create new storage pool with desired RAID type
4. Restore data from backup

Choose wisely at setup — this decision is essentially permanent for that storage pool.

Recommendations by Use Case

Home Media Server / Plex

Recommendation: SHR

• Flexibility to upgrade drives over time
• Can start with smaller drives, upgrade as library grows
• No need for cross-platform compatibility

Home Office / Small Business

Recommendation: SHR or SHR-2

• Budget-friendly upgrade path
• Use SHR-2 for critical business data
• Combine with proper backups (see our Synology Backup Guide)

Photographer / Video Editor

Recommendation: SHR

• Storage needs grow rapidly
• Upgrade path is essential
• Consider SHR-2 for valuable footage

Enterprise / Data Center

Recommendation: RAID 6

• Industry-standard compliance
• Cross-platform compatibility
• Identical drives are standard practice
• SHR not available on xs+ models anyway

Backup Target NAS

Recommendation: SHR

• Flexibility for mixed/spare drives
• Often populated with older drives retired from primary NAS
• SHR handles mixed sizes elegantly

How to Choose: Quick Decision Guide

Answer these questions:

1. Will you ever move drives to non-Synology NAS? → RAID 5/6
2. Using xs+ enterprise model? → RAID 5/6 (SHR not available)
3. Plan to upgrade drives gradually? → SHR
4. Using mixed drive sizes? → SHR
5. All identical drives, no upgrades? → Either works (SHR slightly easier)

If in doubt, choose SHR. It offers strictly more flexibility with no meaningful downsides for home and small business users.

Setting Up SHR or RAID 5 on Synology

During initial DSM setup or when creating a new storage pool:

1. Open Storage Manager
2. Click Create → Create Storage Pool
3. Select RAID type:
   • SHR (recommended for flexibility)
   • SHR-2 (for 2-drive fault tolerance)
   • RAID 5 (for compatibility)
   • RAID 6 (for 2-drive fault tolerance + compatibility)
4. Select drives to include
5. Complete wizard

Use our RAID Calculator to preview capacity before committing.

Frequently Asked Questions

Conclusion: SHR Is the Right Choice for Most Users

For home users and small businesses, SHR is almost always the better choice. The ability to mix drive sizes and upgrade gradually is invaluable — it turns your NAS into a long-term investment that grows with your needs rather than requiring expensive wholesale upgrades.

Choose RAID 5/6 only if you have specific requirements for cross-platform compatibility, enterprise compliance, or are using an xs+ model that doesn’t support SHR.

Whichever you choose, remember that RAID is not backup. Both SHR and RAID 5 protect against drive failure, but neither protects against fire, theft, ransomware, or accidental deletion. Always implement proper backups alongside your RAID configuration.

Related Resources

• SHR Explained — Deep dive into Synology Hybrid RAID
• Synology RAID Guide — All RAID levels compared
• RAID Calculator — Calculate capacity for any configuration
• Synology Backup Guide — Protect your data properly
• Best Synology NAS 2026 — Complete buying guide

Last Updated: February 2026