How do I determine if my HDD uses CMR or SMR?

Short answer:

You determine whether your HDD is CMR or SMR by checking the exact model number against the manufacturer’s spec sheet or a trusted community database. Manufacturers rarely print “CMR/SMR” on the label, so the model number is the key.

🔍 The 3 reliable ways to check (ranked by accuracy)

1. Look up the drive’s exact model number on the manufacturer’s spec sheet (most accurate)
Every major brand—Seagate, WD, Toshiba—lists the recording technology in the official datasheet.

WD explicitly states whether a drive is CMR or SMR in their product sheets.

WD Red Plus, Red Pro, Gold, Purple, Black, and Ultrastar lines are CMR.

Some WD Blue and WD Red (non‑Plus) models are SMR.

2. Check community-maintained CMR/SMR databases
NAS and homelab communities maintain lists of thousands of drive models with confirmed recording types.

These databases are often more up-to-date than manufacturer marketing pages.

3. Watch for branding clues
Certain product lines strongly indicate the technology:

“Archive” drives → almost always SMR

NAS‑rated drives (IronWolf, Red Plus, Red Pro) → almost always CMR

High‑performance lines (Black, Gold, Ultrastar) → CMR

🧠 Why this matters

CMR = predictable performance, safe for RAID, NAS, heavy writes

SMR = cheap per TB, but slow under sustained writes and risky for RAID rebuilds

🛠️ If you want, tell me your exact drive model

Give me the full model number (e.g., ST4000DM004, WD40EFAX, HDWG480XZSTA), and I’ll identify CMR vs SMR for your specific HDD.

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https://disk-scout.com/guides/cmr-vs-smr?utm_source=copilot.com

https://support-in.wd.com/app/answers/detailweb/a_id/50697

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