The catch
Synology DiskStation DS425+
Many apps will find the 2GB base memory modest.
Side by side
Synology DiskStation DS425+ vs Synology DiskStation DS925+ Compared: 925+ can use more RAM and attach a separate expansion unit
Quick verdict
A four-drive DSM server built on an Intel J4125 is what the DS425+ suits. Buyers who value ECC memory, a 32GB memory ceiling and a supported DX525 expansion path are better served by the DS925+.
Before you buy
Why, and what it costs you
Protected capacity when all drives are 12TB
Before formatting, this example gives 36TB with Synology DiskStation DS425+ and 36TB with Synology DiskStation DS925+. A different chassis does not increase protected capacity.
Where this comes from
Suppose each SATA bay holds a supported 12TB disk. A two-bay RAID 1 gives the usable capacity of one disk. With three or more drives, RAID 5 usable TB = (drive count minus 1) × 12. The layout is only an illustration. It is not storage that comes included, and it is not a backup.
The catch
Synology DiskStation DS925+
No integrated media engine on the CPU means no hardware transcoding.
Synology DiskStation DS425+
- Why pick it
- The Intel media engine is central to your plan
- supported ram ceiling: you want 6GB
- The catch
- Many apps will find the 2GB base memory modest.
The DS925+ appears here with the optional DX525 expansion unit. Drives and the DX525 are sold separately.
Synology DiskStation DS925+
- Why pick it
- ECC memory or a DX525 expansion path is required
- supported ram ceiling: you want 32GB
- The catch
- No integrated media engine on the CPU means no hardware transcoding.
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What this page compares
Which of DS425+ and DS925+ fits depends on protected storage, included networking and the exact SSD or application layout you need.
It is Intel media hardware against the ECC and expansion platform.
Day to day
How each one fits your routine
Hourly recovery points for a full week change which one fits
Every hourly snapshot kept for seven days comes to 168 points in each protected folder. DS425+ publishes a 128-per-folder limit and cannot hold that full set, while DS925+’s 256-per-folder ceiling can, provided storage and overall system limits also fit. DS925+ is the choice for that exact recovery policy. Otherwise stay with DS425+ and thin out older points on purpose, rather than finding the retention gap when a file is needed.
Where this comes from
Seven multiplied by 24 is 168. Only the recovery-point count is checked here. A snapshot policy still needs free storage and an independent backup strategy, because a local history does not place another copy outside the NAS.
Capacity from expansion comes with conditions once one volume has to exceed 108TB
Say a growing archive has to stay in one volume above 108TB. DS925+ documents a path to that with 32GB RAM plus the required supported drives and expansion hardware, though its supplied 4GB does not meet the memory condition. DS425+ lists a 108TB single-volume maximum. DS925+ is the one for this particular scale plan. DS425+ makes more sense if a smaller volume works and the extra enclosure and memory would go unused.
Where this comes from
What matters is the size of a single volume. Adding up the labels on every drive does not give you that. Synology lists a 200TB option on DS925+ with 32GB memory and 108TB on DS425+. RAID and filesystem overhead stay outside raw drive totals.
Which one fits
Pick the situations that sound like you
Protected archive built from 12 TB disks filling every internal SATA bay
The example puts two disks in RAID 1 and three or more in RAID 5. Before formatting, Synology DiskStation DS425+ yields 36TB, against 36TB for Synology DiskStation DS925+. Swapping the chassis does not add protected capacity.
- Synology DiskStation DS425+
- Similar
- Synology DiskStation DS925+
- Similar
A workstation already at the speed of the faster included Ethernet port
The ports included run at 2.5GbE and 2.5GbE. Read the 100GB calculation together with the real client speed.
- Synology DiskStation DS425+
- Similar
- Synology DiskStation DS925+
- Similar
Multiple local services dividing up the supplied RAM
Synology DiskStation DS425+ ships with 2 GB RAM and supports 6 GB, while Synology DiskStation DS925+ ships with 4 GB and supports 32 GB. Weigh the stated application memory requirement against the supplied configuration before you budget for an upgrade. A bigger RAM capacity does not prove application speed.
- Synology DiskStation DS425+
- Depends
- Synology DiskStation DS925+
- Better fit
Gain five SATA positions with a supported DX525 enclosure
One supported DX525 gives the DS925+ five more SATA positions and lifts the documented bay count from 4 to 9. In this comparison the DS425+ stays a four-bay main enclosure.
- Synology DiskStation DS425+
- Not suitable
- Synology DiskStation DS925+
- Better fit
In practice
Differences you will notice
Protected capacity when all drives are 12TB
Before formatting, this example gives 36TB with Synology DiskStation DS425+ and 36TB with Synology DiskStation DS925+. A different chassis does not increase protected capacity.
How we worked this out
Suppose each SATA bay holds a supported 12TB disk. A two-bay RAID 1 gives the usable capacity of one disk. With three or more drives, RAID 5 usable TB = (drive count minus 1) × 12. The layout is only an illustration. It is not storage that comes included, and it is not a backup.
100GB moved at the speed ceiling of the included port
At line rate, the minimum is 320 seconds for Synology DiskStation DS425+ and 320 seconds for Synology DiskStation DS925+. Real copies take longer. With a 1GbE client the lower bound becomes 800 seconds for both.
How we worked this out
Decimal 100GB × 8 = 800 gigabits. Take the fastest included port rate, 2.5Gbps or 2.5Gbps, and divide 800 by it. Protocol overhead is ignored here only because this is a lower-bound calculation. Optional adapters and aggregated ports are left out.
A separate enclosure belongs in the expansion budget
One supported DX525 gives the DS925+ five more SATA positions and lifts the documented bay count from 4 to 9. In this comparison the DS425+ stays a four-bay main enclosure.
How we worked this out
Maximum for DS925+ with supported expansion = 4 internal bays plus 5 DX525 bays = 9. The expansion unit is bought separately. Confirm pool boundaries, and do not read a performance gain into the bay count.
Option A
Synology, DS425+
Synology DiskStation DS425+
A 4-bay chassis whose fastest documented network path is 2.5 Gbps.
- Best for
- The Intel media engine is central to your plan
Facts we checked
- Supplied RAM: 2GB
- Supported RAM ceiling: 6GB
- Processor: Intel Celeron J4125
- Software and expansion route: DSM
Option B
The DS925+ appears here with the optional DX525 expansion unit. Drives and the DX525 are sold separately.
Synology, DS925+
Synology DiskStation DS925+
This is a 4-bay chassis, and 2.5 Gbps is the fastest network path documented for it.
- Best for
- ECC memory or a DX525 expansion path is required
Facts we checked
- Supplied RAM: 4GB
- Supported RAM ceiling: 32GB
- Processor: AMD Ryzen V1500B
- Software and expansion route: DSM with ECC memory
Spec by spec
Where they really differ
| Spec | Synology DiskStation DS425+ | Synology DiskStation DS925+ | In practice |
|---|---|---|---|
| Supplied RAM | 2GB | 4GB | This figure is the memory already installed, before any upgrade modules are bought. |
| Supported RAM ceiling | 6GB | 32GB | The manufacturer-supported upgrade ceiling for concurrent services is set by this. |
| Processor | Intel Celeron J4125 | AMD Ryzen V1500B | The platform determines the media engines, the application architecture and the concurrency. |
| Software and expansion route | DSM | DSM with ECC memory | Pick the applications and supported add-ons the job calls for. |
| SATA bays with supported expansion | 4 | 9 | Compatible hardware bought separately, plus a supported pool layout, is what expansion takes. |
Trade-offs
What each pick costs you
With Synology DiskStation DS425+
- 10GbE is not available as an upgrade.
With Synology DiskStation DS925+
- Expanding gives you more bays. It does not add 10GbE.
Change of plan
When the answer changes
The Intel media engine is central to your plan
Go with Synology DiskStation DS425+. An Intel Celeron J4125 with an integrated media engine powers the DS425+. Before relying on that feature, confirm whether the media application supports hardware transcoding.
ECC memory or a DX525 expansion path is required
Go with Synology DiskStation DS925+. ECC memory comes supplied with DS925+, which also supports a separately purchased DX525 that takes the documented SATA-bay count from four to nine. Put the expansion enclosure in the budget.
Decision guide
How to decide
First, pin down the storage layout you need
A four-drive DSM server built on an Intel J4125 is what the DS425+ suits. Buyers who value ECC memory, a 32GB memory ceiling and a supported DX525 expansion path are better served by the DS925+.
Count what the drive budget allows
Protected capacity is basically the same across the four internal SATA bays. Reaching nine bays on the DS925+ takes a separate DX525 purchase, so put that external chassis in the budget.
Look at the client and apps you will really use
No integrated graphics engine for Intel-style hardware media transcoding comes with the Ryzen V1500B in the DS925+. If the remote media workload requires conversion, plan on direct play or a separate transcoding computer.
What this page can’t tell you
- Capacity examples assume equal 12TB drives, counted before formatting, snapshots and filesystem overhead.
- Treat Ethernet calculations as lower bounds, since disk performance, network protocol and other traffic add time.
- Neither application speed nor a VM count follows from memory capacity alone.
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 DS425+ |
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| Synology DiskStation DS925+ |
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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 DS425+
The Intel media engine is central to your plan
See price & reviews on AmazonThe DS925+ appears here with the optional DX525 expansion unit. Drives and the DX525 are sold separately.
Synology DiskStation DS925+
ECC memory or a DX525 expansion path is required
See price & reviews on AmazonEach link opens in a new tab.
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