DS916 & DS1921 inquiry

[Enquiries]

Dear team
I hope you can help us with 2 hopefully easy inquiries.
Today our family uses 3x DS916 NAS devices for our family data (e.g., photos, family movies, data backup etc.).
We would like to increase our storage capacity. When we bought the devices we set them up with 2x 8tb raid 1 and then we added another 2x 16tb raid 1.
1. the DX513 is no longer around and we'd like to know if the DX517 is compatible with our DS916 devices, s owe can buy 3 expansion devices for each NAS. Then we'd like to know if we can buy standard drives (our preference would be for 24x Ultrastar DC HC590 24TB in SHR mode for usage with the DX517)
2. As an alternative we found some good offers on some older DS1821+ devices, but again we cannot find any information if they would work with Ultrastar DC HC590 24TB in SHR mode as the official compatibility list is very small. Could you help us clarify this point or does the DS1821 only works with a very limited list of enterprise hard drives?
kostas and eleni

[ed]

Regarding your first question, the DX517 expansion unit will not be compatible with the DS916 unless the connection interface matches. Unfortunately, the DS916 is designed to work specifically with the DX513 or DX213. While the DX517 is a newer model, it is unlikely to work due to differences in connection types between the units. You will need to look into options that match the connection compatibility of your current setup.

As for your second question about the DS1821+ and the Ultrastar DC HC590 24TB drives, although the official compatibility list may be small, the DS1821+ is generally more flexible with enterprise-level drives, and the Ultrastar drives should technically work with this model. However, since they are not officially listed, there is no guarantee of full compatibility. Synology’s official lists tend to be more conservative, but it’s always a good idea to confirm through testing or contact Synology directly for more detailed advice if you decide to go this route.