The catch
Synology DiskStation DS725+
The separately purchased DX525 is needed for extra drive bays.
Side by side
Synology DS725+ vs DS225+: 725+ brings NVMe and expansion, and the starting network ports are the same
Quick verdict
DS725+ is the pick if your two-bay NAS also needs onboard NVMe, supported memory above 6 GB or the option to add a separate DX525 expansion unit. DS225+ makes sense if two SATA drives and its documented application limits handle the job. Networking starts out identical on both, with one 2.5GbE port and one Gigabit port.
Before you buy
Why, and what it costs you
Mirrored archives start with the same drive count either way
With two SATA bays in each chassis, the same pair of compatible drives gives the same nominal RAID 1 capacity.
Where this comes from
On either system, a mirror of two equal 12 TB drives gives 12 TB before overhead.
The catch
Synology DiskStation DS225+
Onboard NVMe sockets are absent.
Synology DiskStation DS725+
- Why pick it
- Install two NVMe drives without giving up either SATA bay
- Run ECC memory, up to the supported 32 GB maximum
- The catch
- The separately purchased DX525 is needed for extra drive bays.
Synology DiskStation DS225+
- Why pick it
- Stick with DSM on two SATA drives
- Rely on the 2.5GbE networking it already has, with no NVMe or DX525 in the plans
- The catch
- Onboard NVMe sockets are absent.
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What this page compares
Weigh the Synology DS725+ and DS225+ on a two-drive mirror, onboard NVMe, later expansion and where the six-gigabyte RAM limit falls.
DS725+ is the pick if your two-bay NAS also needs onboard NVMe, supported memory above 6 GB or the option to add a separate DX525 expansion unit. DS225+ makes sense if two SATA drives and its documented application limits handle the job. Networking starts out identical on both, with one 2.5GbE port and one Gigabit port.
Which one fits
Pick the situations that sound like you
Hold on to two HDDs and add two onboard NVMe drives
No M.2 sockets are on DS225+.
- Synology DiskStation DS725+
- Better fit
- Synology DiskStation DS225+
- Not suitable
Run a supported 8 GB memory configuration
A 6 GB maximum is published for DS225+.
- Synology DiskStation DS725+
- Better fit
- Synology DiskStation DS225+
- Not suitable
Plan on an optional DX525 expansion unit
That expansion port is documented only for DS725+.
- Synology DiskStation DS725+
- Better fit
- Synology DiskStation DS225+
- Not suitable
Serve a two-drive mirror over one 2.5GbE connection
The rated native link is the same on both.
- Synology DiskStation DS725+
- Good
- Synology DiskStation DS225+
- Good
In practice
Differences you will notice
Mirrored archives start with the same drive count either way
With two SATA bays in each chassis, the same pair of compatible drives gives the same nominal RAID 1 capacity.
How we worked this out
On either system, a mirror of two equal 12 TB drives gives 12 TB before overhead.
DS225+ support cannot cover an 8 GB requirement
A 6 GB ceiling is published for DS225+, while DS725+ supports up to 32 GB.
How we worked this out
8 GB is 2 GB more than 6 GB. Neither selected package comes with 8 GB unless it is upgraded.
Two M.2 sockets let the two-drive SATA layout stay as planned
Two onboard NVMe drives fit in DS725+ alongside its two SATA drives. DS225+ has no onboard M.2 sockets.
How we worked this out
Two SATA plus two NVMe connectors are set against two SATA only.
Option A
Synology, DS725+
Synology DiskStation DS725+
This two-bay DSM system has ECC memory and two NVMe sockets, with a separate DX525 as the expansion path.
- Best for
- Install two NVMe drives without giving up either SATA bay
Facts we checked
- SATA bays inside: 2
- NVMe sockets onboard: 2
- Memory installed: 4 GB DDR4 ECC
- Largest supported memory: 32 GB
Option B
Synology, DS225+
Synology DiskStation DS225+
A 2-bay chassis whose fastest documented network path is 2.5 Gbps.
- Best for
- Stick with DSM on two SATA drives
Facts we checked
- SATA bays inside: 2
- NVMe sockets onboard: 0
- Memory installed: 2 GB DDR4 non-ECC
- Largest supported memory: 6 GB
Spec by spec
Where they really differ
| Spec | Synology DiskStation DS725+ | Synology DiskStation DS225+ | In practice |
|---|---|---|---|
| Internal SATA bays | 2 | 2 | Stepping up brings no extra internal HDD bays. |
| Onboard NVMe sockets | 2 | 0 | Only in DS725+ can dedicated M.2 drives sit alongside both SATA drives. |
| Installed memory | 4 GB DDR4 ECC | 2 GB DDR4 non-ECC | Capacity and memory type at the start are different in the standard packages. |
| Supported memory maximum | 32 GB | 6 GB | DS225+ support falls short of an 8 GB application requirement. |
| Dedicated expansion-unit support | One optional DX525, seven total SATA bays | No DX525 expansion port listed | A separate unit is needed for expansion, and the original chassis does not grow. |
| Native network ports | One 2.5GbE and one 1GbE | One 2.5GbE and one 1GbE | Faster native Ethernet does not come with the higher model number. |
Trade-offs
What each pick costs you
With Synology DiskStation DS725+
- A socket alone does not guarantee a qualified NVMe storage pool.
With Synology DiskStation DS225+
- The ceiling for supported RAM is 6 GB.
Change of plan
When the answer changes
Any of NVMe, ECC or RAM above 6 GB is necessary
Go with Synology DiskStation DS725+. The documented hardware path comes with DS725+.
My applications are covered by two SATA drives and the lower memory limit
Go with Synology DiskStation DS225+. That narrower configuration is met by DS225+.
I assume either selected package brings native 10GbE
Neither model fits. The built-in fast port is 2.5GbE on each.
Decision guide
How to decide
Pick the DS725+ if your two-bay NAS must also offer onboard NVMe, supported memory above 6 GB or the separate DX525 expansion route. The DS225+ is enough when two SATA drives and its documented application limits cover what you need to do. Both begin with the same network layout of one 2.5GbE connection and one Gigabit connection.
Mirrored archives start with the same drive count either way
Stepping up to the DS725+ will not multiply your starting HDD capacity if all you need is a two-drive mirrored archive. What it adds has to come from memory, M.2 sockets or a future expansion unit. Plan space for snapshots and a separate backup too. RAID 1 holds a second copy within the array, yet it cannot guard against every way of losing data.
DS225+ support cannot cover an 8 GB requirement
Let the memory requirement of your applications decide. When a supported service calls for 8 GB, only the DS725+ has the documented upgrade headroom, and the DS225+ falls outside that supported setup. Plain backup duty gains nothing from the higher limit, so don’t assume it helps. Synology also lists ECC for the DS725+, which counts if you specifically need that memory protection.
Two M.2 sockets let the two-drive SATA layout stay as planned
Say both SATA bays already hold the archive. The DS725+ then gives you separate physical slots for a supported NVMe cache or a qualified SSD pool. Look up the exact SSD and its DSM pool eligibility before you buy. The DS225+ can take SATA SSDs in its current bays, but that alters the original two-HDD layout and does not add independent onboard NVMe positions.
What this page can’t tell you
- There are no matched results for Plex, applications, memory errors, noise or throughput. The mirror example assumes equal, compatible drives and leaves out overhead.
By the numbers
What the data shows
What we found across the NAS devices we compare, plus the checked facts behind each finding.
Show the facts and the math
| Product | Needs it meets | Facts we checked | Sources |
|---|---|---|---|
| Synology DiskStation DS725+ |
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| Synology DiskStation DS225+ |
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Ready to buy
See today’s price and what owners say
Open either model on Amazon for the current price, customer reviews and delivery options.
Synology DiskStation DS725+
Install two NVMe drives without giving up either SATA bay
See price & reviews on AmazonSynology DiskStation DS225+
Stick with DSM on two SATA drives
See price & reviews on AmazonEach link opens in a new tab.
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