CMR vs SMR: The Complete Reference Table
The table below covers the most common hard drive families sold on Amazon. Capacity ranges matter — the same brand and line can be CMR at one capacity and SMR at another.
| Drive Family | Capacities | Technology | NAS / RAID Safe |
|---|---|---|---|
| WD Red Plus | 1TB – 14TB | CMR | ✅ Yes |
| WD Red (non-Plus) | 2TB – 6TB (post-2019) | SMR | ❌ No |
| WD Red (non-Plus) | 8TB+ | CMR | ✅ Yes |
| WD Gold | 1TB – 26TB | CMR | ✅ Yes |
| WD Black | 500GB – 8TB | CMR | ✅ Yes |
| WD Blue | 1TB – 6TB (3.5") | CMR | ✅ Desktop |
| WD Green | All | SMR | ❌ No |
| Seagate IronWolf | 1TB – 20TB | CMR | ✅ Yes |
| Seagate IronWolf Pro | 2TB – 24TB | CMR | ✅ Yes |
| Seagate Exos X-Series | 8TB – 24TB | CMR | ✅ Yes |
| Seagate Barracuda | 2TB – 6TB | SMR | ❌ No |
| Seagate Barracuda | 8TB+ | CMR | ✅ Desktop |
| Seagate Barracuda Pro | All | CMR | ✅ Yes |
| Seagate SkyHawk | 1TB – 20TB | CMR | ✅ Surveillance |
| Toshiba N300 | 4TB – 20TB | CMR | ✅ Yes |
| Toshiba X300 | 4TB – 20TB | CMR | ✅ Yes |
| HGST Ultrastar | All | CMR | ✅ Yes |
Need to find a CMR drive at the best $/TB right now?
The reference table above tells you what's safe — but it doesn't tell you which specific listing on Amazon has the lowest price per terabyte today. Prices shift daily, and the cheapest CMR 8TB drive this week isn't necessarily the same one as last week.
That's exactly what cmrcheck.com tracks automatically:
- CMR/SMR labeled — every listing is tagged at a glance, no research needed
- $/TB sorted — best value CMR drive always at the top
- RAID Safe badge — visual flag on every drive safe for NAS and parity RAID
- Renewed / Third-Party flagged — know if a deal is new vs refurbished
- Updated weekly — prices pulled fresh from Amazon every Monday
Whether you're building a Synology NAS, Unraid server, or a TrueNAS array — filter by CMR, sort by $/TB, and you have your shortlist in 30 seconds.
Browse CMR Drives at cmrcheck.com →Why the WD Red Scandal Changed Everything
In April 2020, Blocks & Files revealed that Western Digital had silently switched WD Red 2TB–6TB drives from CMR to SMR — without changing the product name, packaging, or Amazon listing. NAS users buying replacement drives were unknowingly installing SMR drives into RAID arrays that previously ran CMR.
The consequences were severe: RAID rebuilds that previously took hours began taking days, then timing out. NAS units marked drives as failed mid-rebuild. Data loss followed. Western Digital eventually acknowledged the change and introduced the "WD Red Plus" branding for CMR variants — but the confusion persists because old WD Red stock still circulates on Amazon.
The lesson: never assume. Always verify CMR vs SMR before installing a drive in a NAS or RAID array. The checker above and the drive table are built for exactly this.
Model Number Decoder: WD
Western Digital encodes recording technology in the model number suffix:
| Suffix | Series | Technology |
|---|---|---|
| EFRX, EFPX, EFBX, EFGX | WD Red Plus | CMR |
| EFAX, EFZX | WD Red (original) | SMR |
| FRYZ, KRYZ | WD Gold | CMR |
| EZEX, EZAZ (1-4TB) | WD Blue | Mixed |
| PURP, PURX | WD Purple | CMR |