Best CMR Hard Drives (2026)
CMR (Conventional Magnetic Recording) — also known as PMR (Perpendicular Magnetic Recording) — is the traditional, reliable recording technology that writes data on non-overlapping tracks. It provides consistent read/write speeds and is the only safe choice for RAID arrays, NAS enclosures, and any workload involving sustained writes.
In contrast, SMR drives overlap tracks to increase density, causing severe write slowdowns under sustained load. If you are building a NAS or RAID array, CMR is mandatory.
Live CMR Drive Comparison
Prices updated daily from Amazon. Sorted by lowest cost per TB.
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CMR vs SMR Explained
Not sure about the difference? Read our full CMR vs SMR guide or use the RAID calculator to model your array before buying.
How CMR Works
CMR writes data to non-overlapping tracks in a predictable, linear pattern. Because tracks do not overlap, any track can be rewritten at any time without affecting adjacent data. This gives CMR drives consistent, sustained write speeds and predictable RAID rebuild times.
Why SMR Is Problematic
SMR overlaps tracks to fit more data per platter. When a drive needs to update data mid-track, it must rewrite entire zones — creating a “write cliff” where speeds drop to 10–30 MB/s sustained. In a NAS RAID rebuild, this can stretch a 12-hour job to 3+ days.
Verified CMR Drive Families
Confirmed CMR families include: Seagate IronWolf / IronWolf Pro, Seagate Exos, WD Red Plus / Red Pro, WD Gold, WD Ultrastar, Toshiba N300, Toshiba MG series. The original WD Red (non-Plus) used SMR in some capacities — avoid it.
When SMR Is Actually Fine
SMR is acceptable for single-drive cold storage or backup targets that are written to infrequently and never rebuilt in a RAID. If you are archiving files you rarely touch and prioritize cost-per-TB over write performance, SMR can save you money.