Western Digital CMR (Conventional Magnetic Recording) refers to a type of hard drive technology developed by Western Digital Corporation. CMR drives use traditional magnetic recording methods to store data on a drive’s spinning platter. This differs from other drive technologies like SMR (Shingled Magnetic Recording) which overlap data tracks for higher density.
What is CMR technology?
CMR technology stores data in distinct parallel tracks on a drive platter. Each track is separated from adjacent tracks by a physical boundary. This allows a drive head to write to or read from a track without interfering with nearby tracks.
Some key characteristics of CMR technology:
- Data is written in discrete parallel tracks across the platter
- Tracks are separated by defined physical boundaries
- Drive heads can access any individual track without affecting adjacent tracks
- Simpler data writes compared to overlapping SMR technology
- Higher performance for random write workloads
CMR technology has been used in hard drives for decades and represents a mature, reliable way to store data. The defined track boundaries prevent data interference that can occur with higher density methods like SMR.
How does CMR work?
Here is a high-level overview of how CMR storage works:
- Data is written to a spinning platter coated with a magnetic recording material.
- An electromagnet write head encodes data along concentric tracks on the platter surface.
- Tracks are physically separated to prevent interference between adjacent tracks.
- A magnetoresistive read head detects the magnetic polarity transitions that represent data.
- The head positioning actuator moves heads across the platter to access specific tracks.
- On-board firmware controls the precise timing of read/write head movements.
CMR drives organize data in 512-byte sectors which are stored along the tracks. Each sector stores a fixed amount of user-accessible data plus internal drive metadata needed for error checking and location addressing.
The electromagnet write head polarizes tiny magnetic regions on the platter surface to record binary 1s and 0s. Changing magnetic polarity represents bit transitions. The read head detects these magnetic flux changes to reconstruct the original stored data.
Benefits of CMR technology
Some benefits of Western Digital’s CMR technology include:
- Performance – CMR drives excel at random write workloads because tracks are isolated. The head can quickly access any track location.
- Reliability – Well-defined track boundaries prevent data loss or corruption issues seen in drives using overlapping SMR technology.
- Maturity – CMR technology has been used for decades and is proven, trusted technology.
- Cost-effective – CMR strikes a balance between affordability and performance without resorting to ultra high densities.
- Wide compatibility – CMR is universally compatible with operating systems, controllers, and interfaces.
For typical consumer and commercial applications, CMR offers better sustained performance compared to denser shingled recording methods.
Western Digital CMR vs SMR
Western Digital produces hard drives using both CMR and SMR technology. Here is a comparison between CMR and SMR:
| CMR | SMR |
|---|---|
| Uses distinct, parallel tracks | Overlaps tracks in a shingled pattern |
| Simpler, faster writes | Slower write speeds |
| Handles random writes well | Optimized for sequential writes |
| Mature, proven technology | Newer technology |
| Universally compatible | May have compatiblity issues |
| Cost-effective performance | Prioritizes high capacity |
In summary, CMR offers better performance and compatibility while SMR prioritizes drive capacity. SMR uses a shingled writing approach to safely increase areal density at the cost of write speed.
Western Digital CMR drive families
Western Digital produces a range of CMR-based hard drive families for different applications:
WD Blue HDDs
WD Blue hard drives are designed for everyday use in desktop PCs and laptops. They come in both standard HDD and solid state hybrid variants. Key features include:
- Capacities from 250GB to 6TB
- SATA 6Gb/s or SATA 3Gb/s interfaces
- Buffer sizes from 8MB to 256MB
- 5400 RPM or 7200 RPM spindle speeds
- Designed for 24/7 operation
- 2 year limited warranty
WD Black HDDs
WD Black performance drives deliver high speeds and reliability for gaming rigs and high-end PCs. Notable features include:
- Capacities from 500GB to 14TB
- SATA 6Gb/s and PCIe NVMe interfaces
- Up to 266MB/s sustained transfer rates
- 7200 RPM spindle speed
- 5 year limited warranty
- Dual-core CPUs for processing
WD Purple HDDs
WD Purple drives are engineered for 24/7 surveillance and security systems. Key capabilities:
- Capacities from 1TB to 14TB
- Tuned for write-intensive workloads
- Supports up to 64 HD cameras
- Enhanced vibration tolerance
- 3 year limited warranty
- TLER and ATA streaming support
WD Red HDDs
WD Red NAS drives provide reliability and performance for home and small business NAS systems. Features include:
- Capacities from 1TB to 14TB
- CMR technology (Red Plus models)
- Speeds up to 210MB/s
- NASware firmware
- Supports up to 8 bays
- 3 year limited warranty
WD Gold HDDs
WD Gold datacenter drives deliver robust storage for servers and high-end workstations. Key specs:
- Capacities from 1TB to 14TB
- 7200 RPM with up to 269MB/s speeds
- HelioSeal for power efficiency
- Dual actuator technology
- 5 year limited warranty
- 1.2M hours MTBF rating
Conclusion
Western Digital CMR technology provides a proven, high performance storage foundation for the company’s extensive 3.5″ hard drive portfolio. It strikes an optimal balance between speed, reliability, and cost-effectiveness for most consumer and commercial applications.
Compared to dense shingled recording methods like SMR, CMR delivers wider compatibility, faster operation, and more robustness thanks to its conventional parallel track layout. Western Digital uses CMR technology across their WD Blue, Black, Purple, Red, and Gold HDD families to serve diverse storage needs.
With its longstanding track record and clear technical advantages for common workloads, Western Digital CMR technology will continue providing quality storage solutions into the future even as new technologies emerge.