raid rechner synology

What Is a “RAID Rechner” for Synology?

If you are searching for raid rechner synology, you are usually trying to answer one practical question: “How much storage will I actually get after RAID protection?” Raw drive capacity and usable NAS capacity are not the same thing. RAID reserves part of your total space for redundancy, which protects your data when one (or more) disks fail.

A Synology RAID calculator helps you plan before buying disks. It gives you a quick estimate of:

• Raw capacity (all disks added together)
• Usable capacity (what remains for files)
• Redundancy/parity overhead
• How many disk failures your array can survive

Quick RAID Level Summary for Synology NAS

SHR (Synology Hybrid RAID)

SHR is Synology’s flexible RAID system and the most popular choice for home users and small offices. With equal-size drives, SHR behaves similarly to RAID 1 (2 drives) or RAID 5 (3+ drives). Its key advantage is easier expansion and better use of mixed disk sizes.

SHR-2

SHR-2 provides two-drive fault tolerance. Capacity overhead is higher, but resilience is better for larger arrays where rebuilds take longer. For equal-size drives, it behaves similar to RAID 6.

RAID 0

Maximum capacity and speed, but no redundancy. If one disk fails, all data is lost. Great for scratch data, not ideal for important files.

RAID 1

Mirroring. Strong protection and simple setup. Total usable space is close to one drive (with a standard two-drive mirror).

RAID 5 / RAID 6 / RAID 10

• RAID 5: 1-drive fault tolerance, efficient capacity use, minimum 3 drives.
• RAID 6: 2-drive fault tolerance, safer for bigger arrays, minimum 4 drives.
• RAID 10: mirrored stripe, good performance and protection, requires even number of drives (minimum 4).

How This Calculator Works

The calculator above uses equal-size drive assumptions. That means each disk is treated as the same capacity. This is accurate for many builds (e.g., 4×8TB or 6×12TB), but real-world SHR behavior with mixed disks can be more nuanced.

Formula examples:

• RAID 5: usable = (N − 1) × disk size
• RAID 6: usable = (N − 2) × disk size
• RAID 10: usable = (N / 2) × disk size
• SHR (equal drives): roughly RAID 1 for 2 drives, RAID 5 style for 3+ drives

Practical Buying Advice Before You Build

1. Plan for rebuild time, not just capacity

Modern large disks can take many hours (sometimes much longer) to rebuild. During this period, your array is more vulnerable. That is one reason many users with 6+ disks choose RAID 6 or SHR-2.

2. Keep backups separate from RAID

RAID is availability, not backup. It protects against drive failure, but not accidental deletion, ransomware, filesystem corruption, or theft. Follow the 3-2-1 strategy: multiple copies, multiple media types, and at least one off-site/offline backup.

3. Match your RAID level to your workload

• Media archive: SHR or RAID 5 is often efficient.
• Business-critical data: SHR-2 or RAID 6 for stronger tolerance.
• High random I/O workloads: RAID 10 can be attractive.

4. Think about expansion

If you expect to grow over time, SHR is usually easier for incremental upgrades than fixed traditional RAID levels. Synology’s storage manager lets you expand arrays, but expansion rules differ by configuration.

Example Scenarios

Example A: 4 × 8TB with RAID 5

Raw = 32TB. Usable ≈ 24TB. One disk worth of space is used for parity. You can survive one drive failure.

Example B: 6 × 12TB with RAID 6

Raw = 72TB. Usable ≈ 48TB. Two disks worth of capacity used for parity. You can survive two simultaneous drive failures.

Example C: 2 × 16TB with SHR

Raw = 32TB. Usable ≈ 16TB (mirror-style behavior). Good simple setup for redundancy in a compact NAS.

Limitations to Keep in Mind

• File system and metadata overhead reduce final reported space slightly.
• Manufacturers report decimal TB, while operating systems may display TiB.
• Mixed drive-size SHR pools need more advanced modeling than a simple equal-disk formula.
• Performance depends on NAS CPU, RAM, network speed, and disk type (HDD/SSD), not just RAID.

Final Thoughts

A good Synology RAID plan balances three things: capacity, protection, and future growth. Use the calculator for a quick estimate, then validate your final layout in Synology Storage Manager before deployment. If your data matters, pair your RAID with a tested backup strategy. That combination—not RAID alone—is what delivers true peace of mind.