The catch
Synology DiskStation DS225+
The unit has no M.2 slots.
Side by side
Synology DiskStation DS225+ vs Synology DiskStation DS425+ Compared: 425+ can grow past a two-drive mirror while you keep the same box
Quick verdict
A two-drive mirror suits the DS225+. When the archive needs to grow by adding disks, or supported M.2 storage is planned, the DS425+ is the better DSM choice.
Before you buy
Why, and what it costs you
Protected capacity when all drives are 12TB
In this example, Synology DiskStation DS225+ gives 12TB before formatting and Synology DiskStation DS425+ gives 36TB. The gap is 24TB before filesystem overhead.
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 DS425+
Many apps will find the 2GB base memory modest.
Synology DiskStation DS225+
- Why pick it
- Your growth forecast fits within a two-drive DSM mirror
- m.2 storage slots: you want 0
- The catch
- The unit has no M.2 slots.
Synology DiskStation DS425+
- Why pick it
- Four internal drives or M.2 slots are required
- m.2 storage slots: you want 2
- The catch
- Many apps will find the 2GB base memory modest.
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What this page compares
Which of DS225+ and DS425+ fits depends on protected storage, included networking and the exact SSD or application layout you need.
Capacity growth is what justifies stepping up to four bays and the wider chassis.
Which one fits
Pick the situations that sound like you
Protected archive built from 12 TB disks filling every internal SATA bay
In this example, RAID 1 handles two disks and RAID 5 handles three or more. Synology DiskStation DS225+ comes to 12TB and Synology DiskStation DS425+ to 36TB before formatting. The gap is 24TB before filesystem overhead.
- Synology DiskStation DS225+
- Good
- Synology DiskStation DS425+
- Better fit
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 DS225+
- Similar
- Synology DiskStation DS425+
- Similar
Multiple local services dividing up the supplied RAM
Synology DiskStation DS225+ has 2 GB RAM and supports 6 GB, and Synology DiskStation DS425+ has 2 GB and supports 6 GB. Before budgeting for an upgrade, check the stated application memory requirement against the supplied configuration. More RAM capacity does not by itself establish application speed.
- Synology DiskStation DS225+
- Similar
- Synology DiskStation DS425+
- Similar
Set up an internal SATA array able to survive two drive failures
Four equal 12TB drives in RAID 6 give the DS425+ 24TB before formatting and tolerance of two drive failures. The DS225+ two-drive mirror offers 12TB before formatting and tolerates one drive failing.
- Synology DiskStation DS225+
- Not suitable
- Synology DiskStation DS425+
- Better fit
In practice
Differences you will notice
Protected capacity when all drives are 12TB
In this example, Synology DiskStation DS225+ gives 12TB before formatting and Synology DiskStation DS425+ gives 36TB. The gap is 24TB before filesystem overhead.
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
The lowest possible time at line rate is 320 seconds for Synology DiskStation DS225+ and 320 seconds for Synology DiskStation DS425+. Real copies take longer. Over a 1GbE client, the lower bound rises to 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.
With four SATA bays comes a protection option the DS225+ does not have
Four equal 12TB drives in RAID 6 give the DS425+ 24TB before formatting and tolerance of two drive failures. The DS225+ two-drive mirror offers 12TB before formatting and tolerates one drive failing.
How we worked this out
For RAID 6, (4 minus 2) × 12 = 24TB. For RAID 1, one mirrored copy = 12TB. Each needs an independent backup, and neither capacity figure counts filesystem overhead.
Option A
Synology, DS225+
Synology DiskStation DS225+
A 2-bay chassis whose fastest documented network path is 2.5 Gbps.
- Best for
- keep family photos safe on a two-drive starting setup
Facts we checked
- Storage comes in a 2-bay chassis.
- The fastest network path documented for it runs at 2.5 Gbps.
- It supports serving media through Plex.
- Camera recording works, though how many channels you can license depends on the software and plan you choose.
Option B
Synology, DS425+
Synology DiskStation DS425+
A 4-bay chassis whose fastest documented network path is 2.5 Gbps.
- Best for
- keep family photos safe on a four-drive starting setup
Facts we checked
- Storage fits in a 4-bay chassis.
- The fastest network path documented for it runs at 2.5 Gbps.
- It supports serving media through Plex.
- Camera recording works, though how many channels you can license depends on the software and plan you choose.
Spec by spec
Where they really differ
| Spec | Synology DiskStation DS225+ | Synology DiskStation DS425+ | In practice |
|---|---|---|---|
| SATA drive bays | 2 | 4 | It alters which disk layouts the main enclosure can hold. |
| M.2 storage slots | 0 | 2 | Treat SSD cache and storage pools as a separate plan from the SATA archive. |
| SATA bays with supported expansion | 2 | 4 | Compatible hardware bought separately, plus a supported pool layout, is what expansion takes. |
| Internal SATA RAID 6 layout | Two SATA positions cannot form RAID 6 | At least four SATA positions available | Two member failures can be tolerated by a four-drive RAID 6 layout, though two drives worth of space goes to parity. |
Trade-offs
What each pick costs you
With Synology DiskStation DS225+
- Confirm that your disks are compatible before buying.
With Synology DiskStation DS425+
- 10GbE is not available as an upgrade.
Change of plan
When the answer changes
Your growth forecast fits within a two-drive DSM mirror
Go with Synology DiskStation DS225+. The Celeron J4125 and 2 GB of supplied memory are common to DS225+ and DS425+. DS225+ is the pick when two SATA positions cover the whole protected-capacity plan.
Four internal drives or M.2 slots are required
Go with Synology DiskStation DS425+. Two more SATA positions and two M.2 slots come with DS425+. Before formatting, four equal 12 TB disks can provide 36 TB in RAID 5, against 12 TB from a two-drive mirror.
Decision guide
How to decide
First, pin down the storage layout you need
A two-drive mirror suits the DS225+. When the archive needs to grow by adding disks, or supported M.2 storage is planned, the DS425+ is the better DSM choice.
Count what the drive budget allows
A Celeron J4125 and 2GB RAM at the start are common to both. Four bays widen the storage-layout options, but they do not mean a better processor or more memory.
Look at the client and apps you will really use
A 12TB mirror comes from two 12TB drives, while four 12TB drives can provide 36TB in RAID 5 before formatting. Count the extra disks and a separate backup destination as part of the larger system's budget.
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.
How many fit
Only 8 of the 32 models checked meet every need here: “Four drives to start” and “Keep going after one drive fails”.
8 models fit, out of 32 checkedThe gap in numbers
Synology DiskStation DS425+ lists 4 bays for drive-bay count, 100% more than the 2 bays on Synology DiskStation DS225+.
- Synology DiskStation DS225+
- 2 bays
- Synology DiskStation DS425+
- 4 bays
- Models with this figure
- 18 of 32
Show the facts and the math
How we countedThe count uses each product's current fit ratings for “Four drives to start” and “Keep going after one drive fails”. A need with no documented match is not counted.
How we calculatedThe count covers the main SATA drive bays only. M.2 slots and external expansion units are not included. For context, 18 of 32 models publish comparable figures.
| Product | Needs it meets | Facts we checked | Sources |
|---|---|---|---|
| Synology DiskStation DS225+ |
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| Synology DiskStation DS425+ |
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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 DS225+
Your growth forecast fits within a two-drive DSM mirror
See price & reviews on AmazonSynology DiskStation DS425+
Four internal drives or M.2 slots are required
See price & reviews on AmazonEach link opens in a new tab.
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