Synology Shr Calculator

Estimate the usable storage space of your Synology Hybrid RAID configuration.

1. Configure Your Drives

Enter Drive Sizes:

What is a Synology SHR Calculator?

A Synology SHR calculator is a specialized tool designed to demystify Synology's proprietary RAID technology, Synology Hybrid RAID (SHR). Unlike traditional RAID systems that can be restrictive, SHR offers a flexible and efficient way to manage and scale your storage, especially when using hard drives of different sizes. This calculator helps you forecast exactly how much usable storage you will have, how much is allocated for data protection (redundancy), and if any capacity will be left unused in your specific drive configuration.

This tool is essential for anyone planning a new Synology NAS setup or considering upgrading an existing one. By inputting your drive sizes and choosing an SHR level, you can make informed decisions about your storage purchases and avoid surprises about available capacity. The primary purpose of a synology shr calculator is to translate the complex underlying logic of SHR into simple, understandable numbers.

Synology SHR Formula and Explanation

Synology Hybrid RAID doesn't use a single, simple formula. Instead, it employs a sophisticated algorithm that partitions drives into smaller chunks to maximize storage. The logic is fundamentally different from classic RAID, which typically treats all drives as if they are the size of the smallest drive in the array.

Here's a conceptual breakdown of how the synology shr calculator logic works:

1. Chunk Creation: SHR analyzes all drives and breaks them down into smaller logical blocks. For instance, it identifies the smallest drive size and creates a primary RAID array (similar to RAID-5 for SHR-1 or RAID-6 for SHR-2) using a chunk of that size from every drive.
2. Redundant Slicing: From the remaining capacity on the larger drives, SHR creates secondary arrays. It groups leftover chunks from multiple drives to form additional RAID-1, RAID-5, or RAID-6 arrays, extracting usable space that would be wasted in a traditional RAID setup.
3. Aggregation: The usable capacity from all these underlying arrays is combined to give you the total usable space.

This intelligent partitioning ensures that the maximum possible space is utilized for both storage and protection. For more technical details, you might consult a Synology RAID Calculator for official figures.

SHR Calculation Variables

Variable	Meaning	Unit	Typical Range
Drive Sizes	The individual capacity of each hard drive in the array.	TB or GB	1 TB – 22 TB+
SHR Level	The level of fault tolerance. SHR-1 protects against one drive failure, while SHR-2 protects against two.	N/A	SHR-1, SHR-2
Usable Space	The total storage capacity available for your data.	TB or GB	Varies based on inputs
Protection Space	The total storage capacity used for data redundancy to protect against drive failure.	TB or GB	Equal to 1 or 2 largest drives (conceptually)

Practical Examples

Example 1: SHR-1 with Mixed Drives

Let's see how the synology shr calculator handles a common scenario: a 4-bay NAS being upgraded over time.

• Inputs:
  • Drive 1: 4 TB
  • Drive 2: 4 TB
  • Drive 3: 8 TB
  • Drive 4: 8 TB
  • RAID Type: SHR-1 (1-drive fault tolerance)
• Results:
  • Total Raw Capacity: 24 TB
  • Usable Space: 16 TB
  • Protection Space: 8 TB
  • Unused Space: 0 TB
• Explanation: SHR creates a RAID-5 array using 4 TB from all four drives, yielding (4-1) * 4 = 12 TB. It then takes the remaining 4 TB chunks from the two larger drives and creates a RAID-1 array, yielding an additional 4 TB. Total usable is 12 + 4 = 16 TB.

Example 2: SHR-2 with Five Drives

Now, consider a more robust setup with two-drive fault tolerance.

• Inputs:
  • Drive 1: 6 TB
  • Drive 2: 6 TB
  • Drive 3: 6 TB
  • Drive 4: 10 TB
  • Drive 5: 10 TB
  • RAID Type: SHR-2 (2-drive fault tolerance)
• Results:
  • Total Raw Capacity: 38 TB
  • Usable Space: 18 TB
  • Protection Space: 20 TB
  • Unused Space: 0 TB
• Explanation: SHR-2 first creates a RAID-6 array using 6 TB from all five drives, yielding (5-2) * 6 = 18 TB of space. The remaining 4 TB from the two larger drives cannot form a redundant array (as SHR-2 needs at least 4 drives for a RAID-6-like slice), but in this specific case, the algorithm is smart enough to use all space. In a less optimal mix, space could be wasted. For an alternative view, you may want to compare SHR vs RAID in detail.

How to Use This Synology SHR Calculator

Using our calculator is straightforward. Follow these steps to plan your storage array:

1. Select RAID Type: Choose between SHR-1 (the most common, protecting against a single drive failure) and SHR-2 (for enhanced protection against two simultaneous drive failures).
2. Choose Storage Unit: Select whether you are entering your drive sizes in Terabytes (TB) or Gigabytes (GB). The results will be displayed in the same unit.
3. Add Your Drives: The calculator starts with two drive inputs. Use the "+ Add Drive" button to add more slots for each drive you plan to install. If you make a mistake, use the 'X' button to remove a drive.
4. Enter Drive Sizes: Input the capacity of each drive into the respective fields. The calculator will update in real-time.
5. Interpret the Results:
   • Total Usable Space: This is the primary result—the actual space you'll have for your files.
   • Intermediate Values: Check the space allocated to protection and any potentially wasted space.
   • Storage Chart: The visual bar chart gives you an at-a-glance understanding of how the total raw capacity is allocated.
6. Reset: Click the "Reset" button to clear all inputs and start over with the default configuration.

Key Factors That Affect SHR Capacity

The final usable capacity in an SHR volume is influenced by several key factors. Understanding them is crucial for effective storage planning with any synology shr calculator.

• SHR Level: SHR-1 reserves capacity equivalent to one drive for protection. SHR-2 reserves capacity equivalent to two drives. This is the biggest factor in the usable space vs. protection trade-off.
• Number of Drives: The more drives you have, the more efficiently SHR can create redundant arrays. An array with five drives is generally more space-efficient than one with three drives.
• Size of the Smallest Drive: The smallest drive in the array often dictates the size of the initial, largest RAID chunk created by SHR.
• Mix of Drive Sizes: While SHR excels with mixed drives, certain combinations are more optimal than others. For example, adding one very large drive to a pool of small drives may result in some temporarily unusable space until a second large drive is added to create a new redundant pair.
• Minimum Drive Count: SHR-1 requires a minimum of two drives to provide redundancy. SHR-2 requires a minimum of four drives.
• Future Expansion Plans: Using SHR makes future expansion easier. You can replace smaller drives with larger ones and the volume will expand, a process much more complex with traditional RAID. If you need help choosing a NAS, check out a NAS selector tool.

Frequently Asked Questions (FAQ)

1. What is the main difference between SHR and RAID-5?

SHR is functionally similar to RAID-5 when all drives are the same size. The key difference is that SHR can optimize storage by using the full capacity of mixed-size drives, whereas RAID-5 would treat all drives as being the size of the smallest one. This is a core reason to use a synology shr calculator for planning.

2. How many drives can fail in SHR-1 vs. SHR-2?

SHR-1 provides fault tolerance for one drive failure. SHR-2 provides fault tolerance for two simultaneous drive failures, offering a higher level of data protection.

3. Why does the calculator show "Unused Space"?

Unused space can occur in specific scenarios where SHR cannot create a redundant array from the leftover "chunks" of larger drives. For example, in an SHR-1 volume, if you have three 2TB drives and one 4TB drive, the extra 2TB on the largest drive will be unused until you add another 4TB (or larger) drive to the array.

4. Can I start with SHR-1 and change to SHR-2 later?

Yes, Synology allows you to change an SHR-1 volume to an SHR-2 volume, provided you have enough drives (a minimum of four is required for SHR-2) and add at least one more drive to the array during the conversion process.

5. What is the minimum number of drives for SHR?

For SHR-1, you need a minimum of two drives to have data redundancy (it will function like RAID-1). For SHR-2, you need a minimum of four drives.

6. Do I have to use the same brand or speed of drive?

No, you can mix brands and speeds (e.g., 5400 RPM and 7200 RPM). However, the performance of the array will be limited by the slowest drive. It is generally recommended to use NAS-grade drives from the Synology compatibility list.

7. Does this synology shr calculator account for system reserved space?

This calculator shows the raw calculated capacity. In a real-world Synology NAS, a small amount of space on each drive is reserved for the DSM operating system and file system metadata (e.g., Btrfs or ext4). Your final volume size will be slightly smaller than the number shown here.

8. Is SHR slower than traditional RAID?

The performance of SHR is generally comparable to its traditional RAID counterparts (RAID-5/6). For most home and small business use cases, any performance difference is negligible and far outweighed by the flexibility and storage optimization benefits of SHR.

Related Tools and Internal Resources

Planning your data storage solution involves more than just capacity. Here are some other resources that might be helpful:

• RAID vs. SHR Comparison: A detailed article breaking down the pros and cons of Synology's Hybrid RAID compared to traditional RAID levels.
• NAS Selection Guide: Not sure which Synology model is right for you? This guide helps you choose based on your needs.
• Data Backup Strategy Planner: Learn about the 3-2-1 backup rule and how to implement it with your Synology NAS.
• Plex Server Performance Guide: Tips on how to optimize your NAS for media streaming with Plex.
• Network Speed Calculator: Estimate file transfer times over your local network.
• Cloud Sync Cost Estimator: Compare the costs of backing up your NAS to different cloud services.