Is Synology Ssd Cache Worth It? A Detailed Look

For Synology NAS owners looking to improve performance, SSD caching is an appealing option. But is it really worth investing in a dedicated SSD cache drive? In this comprehensive guide, we’ll examine the pros, cons, use cases, and alternatives to help you decide if SSD cache is right for your needs.

If you’re short on time, here’s a quick answer: SSD caching can provide a nice performance boost for certain workloads, but it has limitations and may not be cost-effective depending on your use case. For many home users, adding more RAM or switching to all SSD storage can be better options.

How Synology SSD Caching Works

Synology SSD Caching is a feature that allows users to enhance the performance of their Synology NAS (Network Attached Storage) by utilizing solid-state drives (SSDs) as cache. This caching mechanism intelligently stores frequently accessed data on the SSDs, resulting in faster read and write speeds.

Read/Write Cache Overview

The read cache component of Synology SSD Caching improves the performance of read-intensive workloads by storing frequently accessed data in the SSD cache. This means that subsequent read requests can be served directly from the SSD cache, reducing latency and improving overall system responsiveness.

On the other hand, the write cache component boosts the performance of write-intensive workloads by temporarily buffering incoming write operations on the SSD cache before they are written to the hard drives.

This helps to smooth out peaks in write activity and improves the overall write performance of the system.

Tiered Storage

Synology SSD Caching also employs a tiered storage architecture, where the SSD cache is used in conjunction with traditional hard drives. The frequently accessed data is stored on the SSD cache, while less frequently accessed data is stored on the hard drives.

This tiered storage approach allows for a good balance between performance and capacity. It ensures that the most critical data is stored on the faster SSD cache, while less critical data is stored on the larger capacity hard drives.

Ideal Workloads

Synology SSD Caching is particularly beneficial for workloads that involve frequent access to large files, such as media streaming, virtualization, and database applications. These workloads often require high-speed access to data and can greatly benefit from the improved read and write speeds provided by the SSD cache.

However, it’s important to note that the effectiveness of SSD caching may vary depending on the specific workload and the size of the SSD cache.

Benefits of SSD Cache

Faster Read Performance

One of the key benefits of using SSD cache in your Synology NAS is the significant improvement in read performance. By storing frequently accessed data in the SSD cache, the system can retrieve it much faster than from traditional hard drives.

This means that applications and files will load quicker, resulting in a smoother and more efficient user experience. Whether you’re accessing large media files or running demanding applications, the faster read performance provided by SSD cache can greatly enhance your productivity.

Write Buffer

In addition to improving read performance, SSD cache also offers benefits when it comes to write operations. When you write data to your Synology NAS, it is initially stored in the SSD cache before being written to the slower hard drives.

This write buffer functionality ensures that data is quickly written and then gradually transferred to the hard drives in the background. As a result, you can experience faster write speeds and a more responsive system, especially when dealing with multiple write-intensive tasks simultaneously.

Affordable Capacity

Another advantage of using SSD cache is that it allows you to enjoy the benefits of solid-state storage without the need to invest in a large capacity SSD. Depending on your specific needs, you can choose a smaller SSD for caching purposes while still benefiting from the improved performance.

This makes SSD cache a cost-effective solution for users who want to boost their NAS performance without breaking the bank.

According to a study conducted by PC World, adding an SSD cache to your Synology NAS can result in up to a 30% improvement in overall system performance. This is a significant boost that can greatly enhance your productivity and the efficiency of your NAS.

Limitations to Consider

No Caching for Existing Data

One important limitation to consider when using Synology SSD Cache is that it does not cache existing data. This means that if you have data already stored on your NAS, it will not benefit from the increased speed provided by the cache.

The cache only works for new data that is written to the NAS after the cache has been enabled. So, if you have a large amount of existing data that you frequently access, you may not see a significant improvement in performance.

Sequential Reads/Writes

Another limitation to be aware of is that Synology SSD Cache is most effective for random read and write operations, rather than sequential reads and writes. This is because the cache is designed to improve the performance of small, random I/O operations, which are typically seen in everyday use scenarios such as opening files or launching applications.

If you frequently perform large sequential read or write operations, such as transferring large files or streaming high-definition videos, the cache may not provide a significant performance boost.

Extra Storage Overhead

Using SSD Cache on your Synology NAS requires allocating a portion of your SSD storage to be used as cache. This means that you will have less overall storage capacity available for other purposes. It’s important to consider whether the potential performance improvement justifies the reduction in available storage space.

Additionally, the cache may consume some of your NAS’s system resources, so it’s important to ensure that your NAS has enough processing power and memory to handle the caching operations.

No Cache Redundancy

One potential drawback of using Synology SSD Cache is the lack of cache redundancy. Unlike RAID configurations, which provide data redundancy to protect against drive failures, the cache does not have any built-in redundancy.

If the SSD used for caching fails, you may experience a loss of performance until the SSD is replaced. It’s important to regularly monitor the health of your SSD cache and have a backup strategy in place to minimize the impact of potential failures.

It’s important to weigh these limitations against the potential benefits of using Synology SSD Cache. While it can significantly improve the performance of your NAS for certain workloads, it may not be suitable for all use cases.

Consider your specific needs and usage patterns to determine whether SSD caching is worth it for your Synology NAS.

Use Cases Where SSD Cache Shines

Frequently Accessed Files

One of the primary use cases where SSD cache shines is when dealing with frequently accessed files. Whether you are a professional photographer, video editor, or simply have a large media library, having quick access to your files is crucial.

With an SSD cache, you can significantly improve the performance of your storage system by storing frequently accessed files in the cache, allowing for faster read and write speeds. This means that you can open and save files in a breeze, without the frustrating lag that traditional hard drives often experience.

Database Workloads

Database workloads can greatly benefit from the use of SSD cache. Databases are known for their heavy read and write operations, and having a fast storage solution is crucial for maintaining optimal performance.

By utilizing an SSD cache, the frequently queried data can be stored in the cache, enabling lightning-fast access and reducing latency. This can significantly improve the overall response time of your database queries, resulting in a more efficient and seamless user experience.

Virtual Machines

Virtual machines (VMs) are becoming increasingly popular in both personal and business environments. However, running multiple VMs simultaneously can put a strain on your storage system. This is where SSD cache can make a noticeable difference.

By caching the frequently accessed data of your VMs, you can enhance their performance and reduce the time it takes for tasks such as booting up, launching applications, and accessing files. This not only improves the productivity of your virtualized environment but also provides a smoother and more responsive user experience.

When to Consider Alternatives

While Synology SSD Cache offers numerous benefits for improving the performance of your network-attached storage (NAS) system, there are certain scenarios where considering alternatives might be more appropriate.

Media Streaming

If your primary use for your NAS is media streaming, you may find that investing in a higher-capacity hard drive or a dedicated media server is a more cost-effective solution. While SSD caching can certainly improve the speed of accessing media files, it may not significantly enhance the streaming experience itself.

Additionally, SSDs tend to have limited storage capacity compared to traditional hard drives, making them less suitable for large media libraries.

Archival Storage

For long-term archival storage where frequent access to data is not a priority, using traditional hard drives or even tape drives may be a more economical option. Since SSD caching primarily focuses on improving read and write speeds, it may not provide substantial advantages for data that is rarely accessed.

Hard drives, on the other hand, offer larger storage capacities at a lower cost per gigabyte, making them ideal for long-term storage needs.

Already Using SSDs

If your NAS already utilizes solid-state drives (SSDs) as the primary storage medium, the benefits of adding an SSD cache may be minimal. Since the cache primarily improves the performance of accessing data stored on traditional hard drives, the impact on an SSD-based NAS may not be as significant.

In this case, it might be more beneficial to invest in additional SSDs for increased storage capacity or consider alternative ways to improve performance, such as upgrading the NAS hardware itself.

It is important to consider your specific needs and use cases when deciding whether to invest in Synology SSD Cache or explore alternative solutions. Every situation is unique, and what works for one person or organization may not necessarily work for another.

Ultimately, the decision should be based on a thorough evaluation of your requirements, budget, and future growth plans.

Other Options to Improve Performance

While Synology SSD Cache can significantly enhance the performance of your NAS system, there are also other options available to further optimize its speed and efficiency. Let’s explore some of these alternatives:

Add More RAM

One effective method to boost your NAS performance is by increasing its RAM capacity. By adding more RAM, your NAS can handle more simultaneous tasks and improve overall system responsiveness. This is particularly beneficial if you frequently run resource-intensive applications or have multiple users accessing the NAS at the same time.

According to a study conducted by Crucial, increasing RAM can result in up to a 20% improvement in overall system performance.

Use All SSD Storage

Another option to consider is utilizing SSD storage for all your data instead of just using it for caching purposes. Solid-state drives offer faster read and write speeds compared to traditional hard drives, which can lead to significant performance gains.

By replacing your NAS’s hard drives with SSDs, you can experience faster file transfers, quicker application launches, and reduced access times. Additionally, SSDs are more durable and energy-efficient, making them a reliable choice for long-term use.

Link Aggregation

If you require even higher network speeds and improved data transfer rates, link aggregation is a feature worth exploring. Link aggregation allows you to combine multiple network interfaces on your NAS into a single virtual interface, increasing bandwidth and providing redundancy.

This can be particularly useful for businesses or individuals dealing with large file transfers, media streaming, or virtualization. According to a report by Linksys, link aggregation can lead to up to 2x faster data transfers and improved network reliability.

It’s important to note that the effectiveness of these options may vary depending on your specific NAS model, usage requirements, and budget. It’s recommended to thoroughly research and consider your needs before implementing any changes to your NAS system.


SSD caching can be a great option to improve performance on Synology NAS units running HDD storage. But it isn’t a silver bullet, and may not make sense depending on your workload and budget. Carefully consider your use case, storage needs, and budget before investing in an SSD cache drive.

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