Synology DiskStation DS923+: capacity calculator
By Devin Chua · Data checked by Owen Nakamura · Updated In the Synology DiskStation DS923+ with 4 × 8 TB in SHR you keep 21.83 TiB usable (24 TB in drive-maker terms), surviving 1 drive failing. The calculator below is preset to the 4 bays and the RAID types DSM 7.x actually offers on this model (including SHR, which uses mixed drive sizes), with the cost to fill in Canadian dollars from live Amazon.ca prices.
As an Amazon Associate we earn from qualifying purchases on Amazon.ca.
Preset for the DS923+: 4 bays, and only the RAID types this model actually supports.
SHR (Synology Hybrid RAID)
That is 24 TB the way drive makers label capacity. Your NAS shows you the smaller number because it counts in powers of two.
Drives: from CA$2,016 for 4 × 8 TB (CA$63.01/TB overall)
What to know about the DS923+
The predecessor many bought for the drive policy, and still the only four-bay DiskStation with a genuine 10-gigabit upgrade slot. The Ryzen R1600 has only two cores: strong as a file store with ECC RAM, weak for many containers.
The DS923+ at a glance
| Bays | 4 × 3.5-inch SATA and 2.5-inch SATA SSD |
|---|---|
| Maximum raw capacity | 96 TB 4 × 24 TB: the largest drive on Synology's compatibility list for this model. With a DX517 expansion the figure rises accordingly. |
| Processor | AMD Ryzen R1600 (2 cores, 4 threads) |
| Memory | 4 GB stock, DDR4 ECC SO-DIMM (2 slots) 32 GB official (2 × 16 GB ECC). In practice 64 GB (2 × 32 GB ECC SO-DIMM) also runs; Synology does not endorse it. |
| M.2 NVMe | 2 slots 2 × M.2 NVMe. NVMe cache is unrestricted; an NVMe storage pool requires a Synology-approved drive (that has always been the case here). |
| Network | 2 × 1GbE, expandable to 10GbE with the E10G22-T1-Mini add-in card |
| RAID types | SHR, SHR-2, Basic, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10 |
| Third-party drives | unrestricted Open. The 2025 drive restriction explicitly does not apply retroactively: Synology confirms it applies “only to new models from 2025.” In the DS923+ every NAS drive runs without restriction. |
SHR is the real reason to buy the DS923+
SHR subtracts only the largest drive from the total, instead of sizing to the smallest like RAID 5. On the DS923+ that means you can start with two drives, add a larger one later, and actually use the gain. UGREEN and QNAP have no equivalent, and with mismatched drives that freedom is quickly worth several hundred dollars. With equal-size drives SHR is arithmetically the same as RAID 5, so there it is simply preference.
RAID 5 or RAID 6 across the DS923+'s 4 bays?
With 4 bays the DS923+ gives you the choice. RAID 5 (or SHR) leaves 3 of 4 drives as usable capacity and survives one failure; RAID 6 spends one more drive for two. The rule of thumb: from 16 TB drives up, the rebuild after a failure runs so long — easily a full day — that a second failure in that window stops being theoretical. That is when RAID 6 earns its cost on the DS923+.
Which drives belong in the DS923+?
CMR NAS drives rated for 24/7 use — Seagate IronWolf, WD Red Plus, Toshiba N300 or their Pro variants. Our drive picks for the DS923+ with live prices show which of those currently offers the best capacity per dollar. If you are working back from a target capacity instead, the drive-count calculator works out how many drives you need.
Frequently asked questions
How much storage is left in the DS923+ with 4 × 8 TB?
About 21.83 TiB usable — 24 TB in drive-maker terms — computed in SHR, the sensible default for this model. It survives 1 drive failing. The gap from the 32 TB raw goes to parity.
Which RAID types does the DS923+ support?
DSM 7.x offers SHR, SHR-2, Basic, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10 on the DS923+. SHR is the one that matters: it lets the DS923+ use mixed drive sizes instead of leveling every drive down to the smallest.
Can I put third-party drives in the DS923+?
Open. The 2025 drive restriction explicitly does not apply retroactively: Synology confirms it applies “only to new models from 2025.” In the DS923+ every NAS drive runs without restriction.
How much memory does the DS923+ take?
It ships with 4 GB (DDR4 ECC SO-DIMM (2 slots)). 32 GB official (2 × 16 GB ECC). In practice 64 GB (2 × 32 GB ECC SO-DIMM) also runs; Synology does not endorse it. There are 2 slots.
Why does my NAS show less than the calculator says?
Because the maker and the OS count differently. A drive maker calls one trillion bytes a TB; the NAS counts in powers of two and calls that a TiB — about 9 percent less. That is why this calculator leads with the TiB figure: it is the number you will read off the screen.
Devin Chua works out which drives, RAM and NVMe cache fit which NAS model at nasdrives.ca, and what the RAID choice means for usable capacity, checked against what is in stock on Amazon.ca.
Data checked by Owen Nakamura, Technical editor (data checking)