CMR or SMR? Check your drive model

How to check whether your drive is CMR or SMR

Copy the model identifier rather than the serial number. A retail family name or capacity alone can cover several products. Open the source beside an exact match and compare its model column with the recording-technology row. The older disclosure dates are shown deliberately: a historical table documents those listed models, without classifying every product sold under the same brand today.

For example, WD's April 2020 disclosure lists WD40EFAX as SMR, while its March 2025 Red Plus brief lists WD40EFPX as CMR. Both are 4 TB entries. That difference is why the checker keeps the complete model identifier. It also lists CMR and SMR BarraCuda models from the same Seagate datasheet; a family-wide guess would be wrong.

If your identifier includes a revision suffix that the table does not show, confirm the base model in the manufacturer's documentation. The checker leaves that full string unmatched. It does not silently discard characters or turn a partial search into a recording-technology answer.

What an unknown result means

Not listed means this index has no exact documented entry. It means neither CMR nor SMR. Check the vendor's product manual or disclosure table and verify the complete model number. An enclosure SKU, USB bridge identifier or serial number is not necessarily the model of the disk installed inside it. Do not select a similar-looking result as a substitute.

NAS entries have a separate purpose: they show a few enclosure specifications from the manufacturer's product page. Their recording result is always drive-dependent. A DS223 or DS124 model number cannot identify the recording technology of an installed hard drive; use the individual disk's model instead. This index does not estimate unsupported models or recommend a purchase from an unmatched query.

Use the result in a NAS shortlist

Recording technology is one input to the decision. Check the appliance's drive compatibility list, the disk's workload rating, its interface, and its startup power specifications separately. A CMR label alone does not establish workload suitability, warranty coverage, usable array capacity or a guaranteed transfer speed.

The CMR or SMR for NAS buying guide explains the write-workload tradeoff. Continue to the NAS buying guide for chassis and controller planning, or the NAS Drive Bay and PSU Calculator to estimate bay and startup-power requirements. For an existing machine that slows during a long copy, use the NAS hardware transfer checks.

Does a large drive cache prove that a disk is SMR?

No. The cited vendor tables list cache and recording technology as separate specifications. Read the recording row for the exact model. This tool does not derive a recording method from cache size, RPM, capacity or a performance graph.

Can I use the table without JavaScript?

Yes. Every model and source link is present in the page without JavaScript. The search only filters those rows in your browser; the lookup does not send the entered model number to a server.