Synology RAID Calculator: How to Use It

  • Post author:WunderTech
  • Post published:May 1, 2024
  • Post last modified:May 10, 2024
  • Post category:Synology
  • Reading time:5 mins read

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One of the most common questions I receive is about the RAID type a new user should configure with their Synology NAS. The truth is, there’s not a single answer that can be applied to everyone, so utilizing the Synology RAID Calculator is the best place to start. As soon as you understand exactly how this tool works, you’ll be able to determine which option is best for you.

What is Redundancy?

Before we look at how to use the RAID calculator, you need to understand what redundancy is. When you utilize RAID, outside of RAID 0 (which basically makes all hard drives into one big hard drive by working together), there is some form of redundancy. This means that one or more drives in the storage pool will be used for redundancy and if any of the drives were to fail on the NAS, you won’t lose any of your data.

Using RAID 5 as an example, one drive is saved for redundancy. When an individual drive fails, no data will be lost. If a second drive fails, you will lose data. When you’re using Synology’s RAID Calculator, you’ll see that a certain number of TBs is for protection, which means that the total number of TBs listed there is for redundancy.

Synology’s RAID Calculator: How and Why You Should Use It

Synology’s RAID Calculator is generally reserved for hypothetical scenarios or planning out your system, but it’s a great way to determine exactly which RAID type you should use. Mainly because you’ll get an accurate number in terms of the total amount of storage you’ll have available. First, add the total number of hard drives that you have. If you’re using mixed-sized drives, add them all.

Synology RAID Calculator: How to Use It

Next, at the bottom, start cycling through the options available. You’ll notice that in some cases, different options will be the same. Using RAID 5 and SHR as an example, they’re the same because both provide one drive of redundancy, but, SHR allows you to use mixed-sized drives and actually use some of the storage, as well as starting off with two drives only (RAID 5 requires 3 total drives).

Synology RAID Calculator: How to Use It

This should give you an estimate in terms of the total usable storage that you’ll have, as well as what will be saved for protection, what might be unused, etc. Until you have a rough estimate on exactly what you can do with the hard drives from a size perspective, you won’t know where to start.

How SHR Provides Flexibility

One option that a lot of people fall back on is either using SHR or SHR-2. SHR (Synology Hybrid RAID) is for flexibility. If you have mixed-sized drives and you actually want to use all of them in one array and use the storage space, you’ll have to use SHR or SHR-2. If you select RAID 5 or RAID 6, you will only be able to use the total of all drives based on the smallest-sized hard drive.

Using this example with two 18TB hard drives, one 14TB, and one 12TB, you’ll see SHR provides a total usable storage space of 40TB while RAID 5 only provides 32.7TB (12TB (10.9) x 4). Simply put, if your goal is flexibility, it almost always makes sense to use SHR.

Synology RAID Calculator: How to Use It

Final Thoughts

There isn’t a single “best” option here. Use the calculator to look at the different scenarios, assess your overall usage, and then try to determine which option is best. After looking at your options, one will stick out as the best overall option for you based on your storage requirements and the total drive bays available.