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Synology NAS RACK RS3621xs + - Review

Manufacturer SYnology has a wide range of home and small business server systems. Today we find the Synology NAS RACK RS3621xs +, a large solution specially designed for large companies that want their own inexpensive server.


One of the four RAM ports on the Synology NAS RACK RS3621xs + motherboard.

The NAS nozzle collects much of the air from the fans to cool the entire chipset.

The One of the four RAM ports on the motherboard of the Synology NAS RACK RS3621xs + has two PCIe ports to add extensions such as a Wi-Fi card or NVMe drive to configure it as a cache.

A top look at the NAS chipset, where you can see how the plastic nozzle collects and redirects the air stream from the fans to the parts of the NAS most prone to heat.

Another aerial view photo, where we can also see the CPU heatsink, in addition to the connection ports.

Here we can see some of the connection ports of the Synology NAS RACK RS3621xs +. We have two Infinity Band expansion ports to be able to merge two other models into a single system in case we want to expand the storage capacity to use a total of 36 disks.

It also has USB 3.0 ports, and two of its LAN cables have a 10 GB / s connection to connect it to the systems that most require this high speed.

Other ports available are four 1Gb / s LANs and a COM port to connect to somewhat outdated units that still use it.

This photo shows more of the ventilation capacity of the Synology NAS RACK RS3621xs +. The entire rear part forms a grid for air to flow.

The NAS has two power supplies so it has redundant power in the event that one of them fails. Power supplies are very easy to remove and replace in the event that they need to be removed for service or replacement.

This is what the Synology NAS RACK RS3621xs + looks like with the chipset case open.

One of the four fan ports, with its fan removed. They have a needle contact so that it is very easy to remove them.

One of the fans that come standard on the NAS.

This is the intermediate partition of the NAS. it is where the four fans are in parallel, easily removable in case they need to be replaced.

Look at the side of the NAS. Its sides to place it in a rack cabinet are only compatible with Synology's proprietary rails, so we cannot use generic or other brands.

Storage drive bays. They come with a safety clip so they won't be accidentally removed.

One of the bays of the Synology NAS RACK RS3621xs +, removing one of the twelve storage units, in this case, a hard drive.

Front look at Synology NAS RACK RS3621xs +. We see its twelve storage bays, in an arrangement of three rows of four drives each.

In this small section we see the power buttons and control lights of the NAS.

The NAS mounted, and connected to the current. Each of the redundant system power supplies has control lights to report its status.


  • Up to 236.273 random read iops.
  • 5819 MB / s sequential throughput.
  • 8-core and 16-thread processor.
  • Certification of VMWare VsPShere, Microsoft HyperV, CityX, Shenserver and Opestacks.
  • Processor Xeon-D 1541 with 8 cores, 16 threads and 2,1 Ghz up to 2,7
  • 8 GB of DCC memory, expandable up to 64.


Synology NAS RACK RS3621xs + experience and conclusion

We've had the Synologi NAS RACK RS3621xs + installed for over two months, and we've constantly put it to the test. It is true that it can handle 236.273 IOPs and a sequential read speed of 5619 MB / s, but the same does not happen in the tests we have carried out. We have used all six Synology discs, we loaded it with three SSD drives, and we increased the IOPs, reaching about 700 IOPs with the SSD units, and 450 with the hard drives. The figure that you have given us is given when using the two Infinity Band expansion ports with two other full drives, in addition to the fact that the number depends on the RAID system used, which in our case is RAID 5.

We clarify that we have had a very good performance, unlike other NAS that we have tested. You can see that both the hardware and software are developed together. But we only see it from a level of demand compared to the level of a company with several dozen workers. It is too much for a small business or a home user, who would benefit from a more restrained and accessible model.

We can only make minor objections. The first is that if we want to install it in a rack cabinet, we will need to use Synology's own rails, because we will not be able to use generic or other brands. Its other downside is not from the Synologi NAS RACK RS3621xs +, but from the Synology ecosystem itself, which has an operating system with an appcenter that still lacks applications compared to other operating systems, and many have to be custom programmed.

  • It is very modular and very easy to handle.
  • Compared with other professional options for companies, its price is very economical.
  • Its speed, expandability and processor are impressive for the price range it is in.
  • It is too much for small business or home use.
  • Its app center is still somewhat short of capabilities.
  • To fit into a rack, you need to use Synology's own rails.

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Benjamin Rosa

Madrileño whose publishing career began in 2009. I love investigating curiosities that I later bring to you, readers, in articles. I studied photography, a skill that I use to create humorous photomontages.

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