RAID Synology Calculator
Plan your storage array by calculating usable space, redundancy, and fault tolerance.
Calculation Results
Total Usable Capacity
Total Raw Capacity
Used for Protection
Fault Tolerance
| RAID Level | Min. Drives | Fault Tolerance | Usable Capacity |
|---|
What is a RAID Synology Calculator?
A raid synology calculator is a specialized tool designed for planning storage configurations on a Synology Network Attached Storage (NAS) device. It allows users to input the number of hard drives, their capacity, and a desired RAID level to instantly see the resulting usable storage space, the amount of capacity dedicated to data protection (redundancy), and the system’s fault tolerance (how many drives can fail without data loss). This is critical for anyone setting up a new NAS, as choosing the right RAID type is a fundamental decision that impacts capacity, performance, and data safety.
This calculator helps users visualize the trade-offs between different RAID levels like SHR, RAID 5, and RAID 6 before committing to a configuration. Understanding these differences is crucial, as changing a RAID type after it has been created can be a complex and time-consuming process.
RAID Synology Calculator Formula and Explanation
The calculation for usable space depends entirely on the selected RAID level. The formulas assume all drives in the array have the same capacity. Our raid synology calculator uses the following logic, where N is the number of drives and C is the capacity of a single drive.
RAID 6 / SHR-2: Usable Capacity = (N – 2) × C
RAID 1: Usable Capacity = C (Capacity of one drive)
RAID 10: Usable Capacity = (N / 2) × C
RAID 0: Usable Capacity = N × C
Here is a breakdown of the variables used:
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| N | Total number of drives | Drives (integer) | 2 – 24+ |
| C | Capacity per drive | TB or GB | 1 TB – 22+ TB |
| Usable Capacity | The final storage space available for your data | TB or GB | Varies based on inputs |
| Protection Capacity | Space reserved for data redundancy/parity | TB or GB | Varies based on RAID level |
Planning your array is the first step. For more details on setup, see this guide on {related_keywords}.
Practical Examples
Let’s explore two common scenarios to understand how the raid synology calculator works in practice.
Example 1: Home User with a 4-Bay NAS
A user has a Synology DS923+ (a 4-bay NAS) and four 8 TB hard drives. They prioritize a balance of capacity and one-drive redundancy.
- Inputs: 4 drives, 8 TB capacity, SHR-1 (or RAID 5)
- Calculation: (4 – 1) × 8 TB = 24 TB
- Results:
- Usable Capacity: 24 TB
- Protection Capacity: 8 TB (space of one drive)
- Fault Tolerance: 1 drive
Example 2: Small Business Prioritizing Data Safety
A small business uses a 6-bay NAS with six 12 TB drives for critical data and needs higher redundancy.
- Inputs: 6 drives, 12 TB capacity, RAID 6
- Calculation: (6 – 2) × 12 TB = 48 TB
- Results:
- Usable Capacity: 48 TB
- Protection Capacity: 24 TB (space of two drives)
- Fault Tolerance: 2 drives
After deciding on a RAID level, the next step is often {related_keywords} to find the perfect hardware.
How to Use This raid synology calculator
Using our calculator is a simple, step-by-step process designed to give you clear results quickly.
- Enter Number of Drives: Input the total count of physical disks you will install in your NAS.
- Set Drive Capacity: Enter the storage capacity of a single drive. For accurate results, assume all drives are the same size, as this is the standard for most RAID arrays.
- Select Capacity Unit: Choose between Terabytes (TB) and Gigabytes (GB) to match your drives’ specifications. Our calculator uses the 1 TB = 1000 GB standard common in marketing, but filesystem formatting will result in slightly less usable space.
- Choose RAID Level: Select your desired RAID configuration from the dropdown. This is the most important choice for determining your final storage outcome.
- Interpret the Results: The calculator will instantly update, showing your Total Usable Capacity, the space used for protection, and the number of drives that can fail. The chart and comparison table provide further visual context for effective {related_keywords}.
Key Factors That Affect RAID Calculations
Several factors can influence the final available storage on your Synology NAS beyond the basic formula.
- RAID Type: This is the single biggest factor. RAID 0 offers maximum capacity but no protection, while RAID 1, 5, 6, and 10 dedicate one or more drives’ worth of space to redundancy.
- Drive Size Consistency: Standard RAID levels (5, 6) require all drives to be the same size. If you use mixed sizes, the array will treat all drives as if they are the size of the smallest drive in the set. Synology Hybrid RAID (SHR) is designed to optimize capacity with mixed-sized drives.
- Number of Drives: The total number of drives directly impacts capacity and which RAID levels are available. For example, RAID 5 requires at least 3 drives, while RAID 6 requires at least 4.
- File System Overhead: The file system itself (like Btrfs or ext4) reserves a small percentage of space for metadata. Btrfs, for example, can reserve around 4% of the volume for its operations, which is not reflected in this calculator.
- System Partition: Synology’s operating system, DiskStation Manager (DSM), creates a hidden system partition on every drive, consuming a small amount of space (approx. 10 GB per drive).
- TB vs. TiB Conversion: Hard drive manufacturers market capacity in terabytes (TB, base-10), but operating systems measure it in tebibytes (TiB, base-2). This results in a 7-10% discrepancy where 1 TB (1000^4 bytes) equals approximately 0.909 TiB. Our calculator uses the TB standard for input but you may see the TiB value in DSM. To learn about SHR’s advantages, you can read up on {related_keywords}.
Frequently Asked Questions (FAQ)
1. What is the difference between RAID 5 and SHR-1?
With drives of the same size, there is no difference in capacity or protection—both offer 1-drive redundancy. SHR-1’s advantage is its ability to optimize storage capacity when you use drives of different sizes, a feature RAID 5 lacks. A raid synology calculator for uniform drives will show identical results for both.
2. Why is the usable capacity in my NAS less than the calculator shows?
This is usually due to two reasons: the TB vs. TiB difference in how storage is measured, and overhead from the file system (e.g., Btrfs) and Synology’s system partition. The calculator provides a pre-formatting estimate.
3. Can I use this calculator for other NAS brands?
Yes. The calculations for standard RAID levels (0, 1, 5, 6, 10) are universal. However, SHR and SHR-2 are proprietary to Synology, so those specific options would not apply to other brands like QNAP or TerraMaster.
4. What happens if a drive fails in a RAID 5 array?
The array enters a “degraded” state. Your data remains accessible, but performance will be significantly reduced because the system has to rebuild data from parity information on the fly. You must replace the failed drive and rebuild the array to restore protection.
5. Is RAID a backup?
No. This is a critical rule: RAID is not a backup. RAID protects against hardware failure (a broken drive), not against file deletion, malware, data corruption, fire, or theft. Always maintain a separate backup of your important data, ideally following the 3-2-1 rule.
6. Which RAID level is best for me?
It depends on your needs. For most home users, SHR-1 or RAID 5 offers a good balance of capacity and safety. For businesses or users with large arrays (6+ drives), SHR-2 or RAID 6 is recommended for its 2-drive fault tolerance. RAID 10 is best for performance-critical tasks like database hosting. Use the raid synology calculator to compare your options.
7. How does the unit switcher (TB/GB) work?
The calculator converts all inputs to a common internal unit (GB) for calculations to ensure accuracy. If you enter 10 TB, it calculates using 10000 GB. The final result is then converted back to the unit you selected for display.
8. Can I add more drives to my RAID array later?
Yes, with Synology SHR and standard RAID types like 5 and 6, you can expand your storage pool by adding new drives, provided your NAS has empty bays. This makes planning for {related_keywords} easier.